I have a friend I’ll call Claire who I refer to as an “if only.” She could stop traffic if only she did oh-so-simple things, like washed her hair more often and never again wore that Russian-babushka-type hat.

I’ve wanted to grab her by her greasy ponytail and scream “Let me help you!”

Instead, I employed these diplomatic nudges that can steer a best friend towards gorgeousness and away from the body glitter.

1. Blame It on Kim Kardashian
When needing to turn a friend onto a much-needed beauty treatment, pick one of her celebrity beauty idols and say she’s a big fan. One of my girlfriends was sporting a serious lady ’stache until I oh-so-casually mentioned that Kim K. tweeted that laser hair removal was a must-have thanks to her Armenian heritage.

2. Make Her Your Salon Plus-one
If your BFF is new to the whole eyebrow threading/facial peel thing, drag her along when you go for yours. For some women, wandering into a spa or salon solo is foreign and scary. But with you as her cosmetic cheerleader, she’ll feel comfortable trying some new grooming practices.

3. Revisit the Past
One girl I know still dresses like she’s in junior high. So I whipped out our 8th grade album and LOL’ed that we used to dress like that. Key words: used to. She took the bait and realized she needs an update, which -- ta da! -- I was happy to help with.

4. Don’t Lie
If she asks (and only if she asks) tell her that yes, you can see her roots, she does have a bit of a unibrow and those pants are too short. It might sting in the moment, but she’ll be grateful you were honest.

5. Swap Smarts
My girl Claire is a killer web designer. One day over lunch, I suggested that we trade expertise -- she could help me redo my website and I could -- oh, I don’t know -- give her a makeover one night while we drank wine spritzers and watched “Glee.” She felt valued instead of attacked, and we both ended up benefiting.

Photo: @iStockphoto.com/Andresr