Denim Fit Model
Credit: Timur Emek/Getty

Behind every perfectly cut pair of jeans, there’s the booty they’re based on—which, if you’ve bought a contemporary pair since 2002, most likely belongs to Natasha Wagner. One of the most sought after fit models in the premium denim business (some of her clients include Re/Done, Paige, and Lucky Brand), her well-balanced, ahem, assets are an ideal starting point for designers to plan out their sizing.

“I’m not waif-like or super curvy—but I still have curves!—so my proportions adjust to a range of body types,” she describes her unique niche in the industry. “And a brand's goal is to make jeans that work for as many people as possible.”

VIDEO: How to Create the Perfect Frayed Hem on Your Jeans

Throughout a career that’s spanned 15 years, that has meant trying on countless different styles and thinking a whole lot about fit. Here, we’ve asked her to look back on her time behind-the-seams (sorry, it was too tempting!) for her thoughts on finding your best blues.

1. Going up or down a size is does not necessarily mean your body has changed.

According to Wagner, a lot of production variables factor into whether a particular piece runs larger or smaller, from the sewing technique, to how much it shrinks down after the initial wash. Fabric, too, is a major factor: “The rigid vintage-inspired trend, especially, means people need to be open to getting a size or two bigger than usual. Unlike with stretchy jeans, you can’t squeeze into a tighter fit.”

2. Don't pull the trigger on a new pair unless you're in love.

“If something is bothering you about the jeans in the fitting room, it won’t go away when you buy them. So don’t settle! The worst thing is paying for something you’re unsure of, and having it sit untouched in your closet.”

3. But still be open to mixing it up.

Even Natasha, who basically gets a sneak peek of every new silhouette before it hits stores, can be skittish about trying something different; like, most recently, switching her second skin stovepipes for a relaxed, vintage-inspired option. “I didn't didn't get the appeal at first, but once I saw other women wearing them, I was inspired—now, I think the cut is so flattering. Since, I’ve learned it’s really fun to try things outside your comfort zone. You might surprise yourself with how good it looks!”

4. Little details go a long way.

Want to set your go-to blues apart? “I think it’s really cool to make denim your own by adding patches or cutting off the bottoms for an unfinished edge. I’ve also noticed something I like to call mullet jeans: raw on the bottom, with the front slightly shorter than the back. You can buy this built into your pants (most labels refer to it as a ‘step hem’), but it's also easy to DIY at home.”

5. When in doubt, go for the higher rise.

“Side spillage over a waistband happens to best of us, but can be can easily be avoided with a higher rise.” While Natasha loves the leg-lengthening benefits of a design that hits above the belly button, she recommends a mid-rise if you don’t like the feeling of extra fabric over your stomach. “The fit isn't that different from a low rise, but it holds you in in a more flattering way."

Follow Natasha Wagner and her adventures in denim on Instagram at @natashajwagner.