Every woman knows there’s nothing frivolous about looking her most beautiful. And that’s even truer when you choose a new hairstyle, shoes, jewelry or even a perfume in ways that help others. Here’s how to look good while doing good:

1. Donate Your Ponytail
Do you admire the short, chic ’dos of stars like Carey Mulligan, Michelle Williams and Halle Berry and wish you had the nerve to chop off your own flowing tresses? Here’s a way to get your courage up. If your ponytail is 8 inches or longer, donate it to the Beautiful Lengths program and it will be turned into a real-hair wig for a woman battling cancer. A partnership between Pantene and the American Cancer Society, the program has collected over 270,000 ponytails and turned them into 18,000 free wigs. (It takes at least six ponies to make a wig.) Got a few long-haired friends who can also use a new look? Host a Beautiful Lengths party and go get your locks cut together.

2. Clean out Your Closet
Refurbishing your wardrobe by getting together with your girlfriends for clothing swaps is a good idea. An even better idea: While you’re trading favorite togs with your BFFs, make a pile of party dresses and accessories to donate to an organization that provides prom dresses for girls who can’t otherwise afford them. (Google “donate my prom dress” and you’ll find organizations like The Princess Project, Donate My Dress and the Fairy Glam Project.) Make a second pile of suits, interview-appropriate separates, shoes, handbags and unopened cosmetics for Dress for Success, the national nonprofit organization that distributes outfits to disadvantaged women who are trying to enter the workforce.

3. Buy One, Give One
There’s no need to shop with a guilty conscience. Instead, seek out retailers that follow the “buy one, give one” concept pioneered by TOMS Shoes. With every pair of shoes you purchase, the company donates a pair to a needy child. (We have our eye on their fall corduroy wedges!) Need a new pair of specs? Buy a pair of $95 prescription glasses at the online boutique Warby Parker and they’ll provide a pair to someone in the world who doesn’t have access to good vision care. And as temperatures start to drop, you might be thinking of dressing up your bed with a new comforter. Purchase one through The Company Store and a homeless child will get one too.

4. Bejewel Yourself
You can deck yourself out in accessories and give to a good cause at the same time. The supermodel Iman has designed a chic baby-blue-and-white version of the lariat bracelets we all used to make in summer camp. All proceeds go to Save the Children’s efforts to treat malnourished children in Iman’s home country of Somalia and throughout East Africa. You can find the $35 Modelinia Beautiful Friends Forever bracelets at the Noir Jewelry online boutique. You’ll be hearing a lot about actress Rooney Mara -- star of the upcoming film The Girl With the Dragon Tattoo -- which will make the striking necklace she designed for eco-friendly jewelry line Kora even more of a conversation piece. Made from dyed recycled cow bone and wrapped with recycled brass and aluminum cuttings, the $95 necklace is crafted by local African artisans. One-hundred percent of the proceeds benefit families in Kenya’s impoverished slums. Find the necklace on the Kora Designs website.

5. Spritz on a Little Bieber
Admit it: You think Justin Bieber is kind of adorable. Now you can wear him behind your ears with Someday, his new scent for women. It’s a catchy, fresh everyday fragrance with notes of mandarin, juicy pear, jasmine, musk and vanilla. Better yet, the sweetness lingers even after the scent fades. All profits go to two of Bieber’s favorite charities: the Make-A-Wish Foundation and Pencils of Promise, which build schools in poverty-stricken areas throughout the world.

Photo: @iStockphoto.com/DawnPoland

J Brand jeans, Gucci sunglasses, Hanky Panky thongs, Diane Von Furstenberg wrap dresses, Stuart Weitzman stilettos, Botkier handbags and TAG Heuer watches: All at a fraction of their retail price. If you’re the kind of woman who finds fashion bargains to be more irresistible than brownies, chances are you’ve already discovered the world of online flash sales. At leading flash sites, like Rue La La, HauteLook, Gilt Groupe and Ideeli, along with dozens of new ones that pop up weekly, high-end fashion is offered for up to 80 percent off.

Shopping a flash sale takes planning and decisiveness. Each limited-time sale lasts for only 24 to 72 hours with the pick of the online litter going almost instantly. Any woman who regularly shops flash sales can tell wrenching tales of the platform sandals or classic trench coat that ended up “In member’s cart” just as she was about to click “Buy.”

Want a competitive edge? Follow these shopping tips from the pros.

Do advance scouting. Many flash sales sites have an “Upcoming” tab that lists the labels that will be going on sale in the next few days. Familiarize yourself with the possible inventory and select your top picks by checking out the current line on department store sites and the designer’s own website.

Be prompt. Online boutiques open their virtual doors the same time every day, so get to know their schedule. New sales at HauteLook and Rue La La go live at 11 a.m. Eastern Standard Time, Gilt Groupe at noon. Have your mouse posed for action. “Sign in early to check out the lists of sales before they go live, and hit refresh right at 12 p.m. ET to enter the sale as soon as it begins,” suggest Alexandra Wilkis Wilson, a founder and chief merchandising officer of Gilt.com.

Use all the tools that are out there, suggests Kerry Bennett, marketing vice president for HauteLook.com. Some sites have mobile apps that allow you to shop on the go. Becoming a Facebook fan or following a site on Twitter can get you perks, like early previews and friends-only sales.

Shop from the bottom up, suggests Wilson. “Most people begin shopping at the top of the page, and those items get snapped up early,” she says. If you’re even considering an item, drop it in your shopping cart immediately. Sites typically give you 10 or 15 minutes before you have to make the purchase. If the piece you want is sold out, use the “Wait list” option. Items frequently become available as shoppers give them up -- or reach their “Time’s up” limit -- and you’ll be notified as soon as that happens.

Make a shopping list. Know what you need to buy, suggests Kim Turner, an image consultant with FashionCents.tv. “Just like with other sales, if you just buy something because it’s on sale, then you’ll find it sitting in the back of your closet, unworn. An unused item is never a bargain,” she says.

Know your body measurements. The dress that hits the mid-thigh of the tall model featured on a shopping site might land just above the knee on you if you’re 5 feet 3 inches tall. Shopping sites generally include the length of garments, and that can be the most reliable predictor of fit. Turner suggests taking four measurements, using pieces in your wardrobe that fit you perfectly: Inseam (measure a pair of pants from crotch to hem); ideal dress length (measure from shoulder to hem); ideal skirt length (run the tape measure from waist to hem), and sleeve length (measure from shoulder to the end of sleeve).

Hats are this summer’s must-have accessory. They will not only add a dash of chic to any daytime outfit -- making even last year’s wardrobe look fresh -- but also protect your skin and hair from the scorching sun. And, as guests at Kate and William’s royal wedding showed, a well-chosen topper can take a cocktail dress or formal gown to new heights of glamour.

Yes, a fascinator -- those small embellished hats that sit adorably just off the side of the head -- can be overdone and look absurd. (That’s right, princess Beatrice, we’re talking about you!) But done with the right proportion of panache and restraint, a fascinator is head-turning -- without being jaw-dropping -- as Victoria Beckham proved with the navy Philip Treacy fascinator she donned when the duke and duchess of Cambridge exchanged vows in Westminster Abbey.

Whether you’re headed off to a beach holiday or a stylish wedding, or just chillin’ in the city, here’s how to choose the right head-topper for you.

A Weekend in the City
Fedora
A fedora with a menswear feel is the perfect way to add a touch of chic on that steamy day spent running errands, hanging in the park or enjoying some sightseeing in a new city. What make this season’s styles fresh are updated fabrics and fine-tuned details. The Origami fedora by Michael Stars, for example, offers a black and cream graphic pattern, while Target’s Xhilaration fedora is a summery shade of green with a paisley scarf above the brim. Traditional fedoras look fresh with a lace or striped grosgrain ribbon band; try them as a stylish counterpoint to a flirty short summer dress.

Cowboy Hat
Another daytime option is the cowboy hat, a fetching look when you’re wearing a halter top or T-shirt with straight jeans, cutoffs or more polished shorts. This year, you can find them in ivory decorated with tortoise-shell links, or in crocheted raffia with a thin leather band. For inspiration, check out the collections at large online boutiques, like Shopbop.com.

Floppy Hat
Less structured floppy hats add a sexy pop to the maxi dress, one of the season’s staples. Kate Spade offers one with an oversized brim and citrus-colored stripes, while Juicy Couture’s woven paper-straw hat features shimmery stripes in combinations like white and gold or orange and natural.

A Day at the Beach
Wide-brimmed Hat
Wide-brimmed hats will always look glamorous on the sand or around a kidney-shaped pool. J. Crew has one with an extra-wide brim and ruby or indigo stripes. Madewell’s version in black straw will take you from floating on a raft at noon to margaritas at sunset.

Tightly Woven Hat
Darker-hued or tightly woven hats offer extra sun protection, but to be sure you’re guarding against damaging UV rays, choose one with a label that says it’s certified UPF 50. UPF stands for ultraviolet protection fabric; it’s the clothing equivalent of the SPF ratings you find on sunscreens.

A Summer Wedding
Fascinator
You don’t need to be attending a royal wedding to show off a fascinator. A hybrid of a hair accessory and cocktail hat, fascinators are made of whimsical materials like feathers, flowers, lace, ribbons, beds or sequins, which are attached to a base and then fastened to a comb, clip or headband. Whether you’re wearing something flouncy and sherbet-hued or a classic black cocktail dress, there is a fascinator that will perfectly complement your look. Find one at websites like FascinatorsNYC.com and FascinatorsByDesign.com (a British site that ships to the U.S.).

If it’s a daytime wedding, consider flowers and lace. For an evening event, go for the drama of sequins and feathers. Just remember to wear the fascinator askew, and not right in the center of your head; that’s part of its off-center charm.

Photo: Getty Images

This summer’s hottest new fashion trends are sexier than ever. Lace tops, body-grazing maxi-dresses and white linen bottoms aren’t exactly lingerie-friendly, however. It can be a challenge to find bras and panties that stay hidden and provide the support we need. But don’t get your panties in a twist! Here’s trend-by-trend advice on how to rock this season’s must-have looks -- without stressing about what lies beneath.

Sheers
Translucent fabrics, lace, and cotton eyelet are all the rage this summer. But unless you choose the right underpinnings, this look can easily cross the line from sensual to silly. Outside of the office, opt for a bra in a hot hue, like mango or chartreuse, making a fashion-forward statement by letting the color show through.

In the workplace, it’s safest to stick with a solid chemise or slip dress, however. Choose pieces in a subtly accenting color, like Cosabella’s heather gray slip under black, or pick an undergarment that matches your top exactly. Steer clear of flesh-toned options. “Your coworker will only be more distracted as he tries to figure out what he is or is not seeing,” says Jenette Goldstein, founder and owner of Jenette Bras, a Los Angeles lingerie boutique.

Flowing Fabrics
Maxi dresses are the “it” item for summer 2011. But be warned: The loose, free-flowing style actually requires some careful planning. “Prepare for an unexpected summer breeze by wearing a pair of cute boy shorts or cheekies,” says Goldstein. You can find these in delicate prints and scallop-trimmed lace at Victoria’s Secret -- or from designers like Hanky Panky, Elle Macpherson and Biatta -- and in super-flirty herringbone print from Samantha Chang.

If the idea of baring panties -- even adorable ones -- makes you squeamish, there is an alternative. “Double-sided Hollywood Fashion Tape can assist in the blow-away challenges,” says Alicia Vargo, founder and owner of Pampered Passions Fine Lingerie, one of the Web’s largest retailers of fine lingerie with a bricks-and-mortar store in Denver, Colo. Simply use the tape to secure looser skirts and dresses to your lower thighs.

Hot Hues
You could wear this summer’s trendiest shades -- honeysuckle, orange and other rainbow-bright colors -- with lingerie you already own. But the experts we spoke with say bright outfits look even chicer when paired with bras in contrasting -- yet equally bold -- hues. “Even if no one sees it, the fact that you know you’re wearing such sensual lingerie will help you exude a sultry confidence,” says Susan Nethero, Oprah’s bra whisperer and founder of the nationwide Intimacy boutiques.

White or Tight
You probably know that white outfits call for nude bras and panties. If you’ve had difficulty finding bras and panties that disappear under a white tee or white jeans, check out MySkins, a lingerie line that offers options in 20 skin-matching tones, from “honey” to “espresso.” When you’re planning on spending the day outdoors, outsmart sweat with the Playtex Breathable Airform Bra or a convertible halter-friendly bra from Breeze Comfort, a line that features perforated bra pads to keep air moving.

When it comes to body-hugging fashion in flimsy summery fabrics, shapewear is a must. If just thinking about donning anything with a control top on a steamy day makes you break out in a sweat, there’s good news: Lingerie companies now offer undergarments that offer support in lightweight, comfortable styles that are actually, believe it or not, sexy. A few to check out: Walcoal Try a Little Slenderness Light Control Camisole, Spanx Haute Contour Lace Thong, Body Wrap Pinup Seamless Bodysuit and Sassy Box Shaper Bottom. Banish bra fat and other bulges with the Unbelievabra tank-like cami from Shapeez or the Vanishing Back Front-Close Nadia underwire bra from Soma Intimates.

Photo: @iStockphoto.com/RelaxFoto.de

Jennifer Lopez and Fergie are rocking Tom Ford aviator-style sunglasses. Jessica Alba and Julianne Moore sport square gold-tone frames from Chloe. And Jessica Simpson can be spotted running errands in oversized titanium frames from the vintage-inspired Dita Eyewear line.

Celebrities can offer inspiration on the season’s coolest sunglass styles. And if you identify a star whose face shape is similar to yours -- an oval Julia Roberts, say, or a heart-shaped Reese Witherspoon -- you can glean suggestions on which shades might flatter your own face.

UV Damage and Your Eyes
Much more than a celebrity fashion accessory, sunglasses are an essential tool in protecting your vision. Studies show that exposure to the sun’s ultraviolet (UV) rays can harm the lens and cornea of the eye, leading to problems -- like cataracts and macular degeneration -- that can impair vision. And the thin skin around the eye and the eyelid itself are especially vulnerable to skin cancer and to sun-induced signs of aging. Dr. Gail Royal, an ophthalmologist in Myrtle Beach, S.C., admits that she sometimes appeals to her patients’ vanity when she discusses the importance of proper sunglass use. “I’ll point out that sunglasses will protect not just against basal cell and squamous cell carcinomas and melanoma,” she says, “but also against the formation of wrinkles like crow’s-feet and the unsightly thickening of the skin that can sometimes be caused by UV exposure.”

Here’s how to choose a pair of sunglasses that will safeguard your eyes and help your skin care regimen.

Look for Complete UV Protection
Whether you spend $200 for a pair of designer sunglasses or buy one off the drugstore rack for $20, both can do an equally good job of blocking harmful ultraviolet rays. Look for a label or sticker that says the lenses block 99 or 100 percent of UVA and UVB rays. Sunglasses with full protection might also say something like, “Lenses meet ANSI Z80-3 blocking requirements,” or “UV 400 protection.” Sunglass boutiques sometimes remove these labels or stickers for a more attractive display. Chances are the shades provide full UV protection; just be sure to ask.

Color Counts If You’re Behind the Wheel
It may seem logical that a darker lens would do a better job of blocking the sun’s harmful rays than a lighter lens, but that turns out not to be the case. The coating that blocks UV radiation is clear, so shades of any hue are equally effective at filtering those rays. Yellow or rose-tinted lenses can, however, make it difficult to distinguish changes in traffic lights. Gray, green and brown lenses minimize color distortion.

Focus on Fit
To block the light that hits your eye from the sides, choose wraparound frames. Your next best bet? Sunglasses with large lenses and wide temples, like the iconic oversized frames Audrey Hepburn wore in Breakfast at Tiffany’s. Whatever the style, frames should fit snugly on your nose and ears without pinching or rubbing, but not so close that your eyelashes hit the lens.

Choose Polarized Lenses If You Water Ski, Surf or Fish
Polarized lenses reduce glare by filtering out the reflected light that bounces off water. Polarization, however, has nothing to do with UV light absorption, so check the label to make sure they provide maximum UV protection. Keep in mind that, when you’re wearing polarized lenses, it may be difficult to read your cell phone, GPS device or a liquid-crystal display on a dashboard or an ATM machine.

Make Sunglasses a Daily Habit
Like sunscreen, sunglasses should be worn whenever you’re outdoors, year-round. “Just as we’ve learned that you can get a really nasty sunburn on an overcast, hazy day,” says Royal, “you’re exposing your eyes to damaging UV rays on these days too.” So, keep a pair of sunglasses in your purse as part of your beauty routine, along with a small tube of sunblock, and your favorite new coral, peach or pink lip gloss.