“Your sleeve is a 26,” Zac Posen tells me as he prods at the arm of my blazer. “Actually, 25 3/4.”

We're perched in a back corner of his atelier for a photo-shoot fitting. Together we've decided that I'll wear a shapely skirt suit, and though it's my size—a 12—it does not fit. The skirt is so tight it won't zip up. The jacket fits in the shoulders but drowns out my waist. And the mermaid shape is so snug I can't walk at all. As you can imagine, I'm embarrassed—and briefly consider running for the door.

But Posen is unfazed. In fact, he's already remeasuring so he can tell where to pin, let out, and take in the garments. "Alterations," he tells me, "are the game changer when it comes to the perfect fit." And once he's done, voila: The skirt zips, the jacket accommodates, and I can move. "The right tailoring can make any garment work for any body," says Posen. "And it can make you feel confident—especially when, these days, a lot of clothing is two-dimensional, but in real life every body is different, and women have curves.”

© Indigital Look better in your clothes

As a size 12, those words hit home for me. I often feel left out by fashion: In a standard size range, a 12 is regularly too tight; in a plus-size range, even the smallest 14 is too wide. I've learned to shop around this conundrum, but I'm still left standing in a fitting room feeling defeated more than I'd like to admit. And I'm not alone. Women of many body types struggle to fit properly into clothing—so let's do something about it! Isn't it time we stop trying to fit into our clothes and have our clothes fit us instead? Here are a few suggestions on how to start:

Step One: Ignore Your Size

That's right—ignore. Sizes vary between countries, companies, and even articles of clothing. The U.S. government has been attempting to fix this problem via regulation since the 1940s, but instead, the situation has actually gotten worse, with the arrival of vanity sizing—in which bigger garments are tagged with smaller numbers to entice customers (that’s why the 00 now exists). “The mentality that the lowest size is best needs to go out the window," says plus-size model and fashion designer Candice Huffine . “It’s just a number that somebody made up"

Her advice? "Try on several sizes, bigger and smaller," she says. “Some people have tag phobia: They don't want to buy a bigger size because of the number on the label. If you care about that, cut the tags out when you get home!”

Step Two: Shop for Your Biggest Part

It’s an easy truth that changes everything: Buy an item to fit the widest part of your body and take the rest of the garment in. That means no more jackets that gape open and muffin-top-inducing jeans. (Amen!)

“I’m a fan of blazers,” says Huffine. “But when I find one that fits through my shoulders and bust, the waist is often too big. I buy for my broadest part, then create an hourglass by taking in the midsection.”

So what does this mean for your shape? If you're pear-shaped, buy to fit your bottom and take in elsewhere. "I have a small waist and bigger hips," says celebrity stylist Sara Paulsen, who's worked with Mindy Kaling . “I often wear A-line and flounce-hem skirts, which balance my proportions. I buy to fit my hip, then take the waist in—I sometimes even nip a fitted skirt right under the butt to create a flattering curve.”

If you're muscular, the widest part of your body may be your shoulders and biceps. "I tend to have to fit my arms in jackets and take the body in," says Hannah Bronfman, the founder of fitness site HBfit.com . “I always buy a size larger and make adjustments.”

Height can also make it more difficult to wear off-the-rack clothing. “It's really hard for short girls to wear midi skirts,” says celebrity stylist Kate Young —whose clients include Selena Gomez and Natalie Portman. “They make you look shorter. Either go maxi—to the floor—or have the hem taken up above the knee.”

Tall women face the opposite dilemma. “Finding clothes that really fit my body has been a lifelong struggle,” says cover girl and denim designer Karlie Kloss . “Growing up, I found that if pants were long enough, they were much too big; if they fit in the waist, they were way too short.” If that sounds like you, buy a length that fits and have a tailor adjust the waist—or look to the solution Kloss herself invented, a Frame Denim line with 40-inch inseams. (Hudson Jeans and the Gap also offer extended lengths.) 

Step Three: Master E-Shopping

When shopping online, it helps to know your bust, waist, and hip measurements; most sites translate their sizes into those numbers. Also, consider brands that take fit into account: Rent the Runway shares photos of customers in each item (with their honest reviews), so you can see how a piece works on a variety of shapes and sizes. There are also companies that help with fitting woes; True Fit, for example, works with brands like Jason Wu and Marc Jacobs to generate suggestions based on your sizes, previous purchases, and its own e-commerce database.

Step Four: Make Your Alterations

The next step is the all-important nipping and tucking. Find a good tailor by asking a trusted boutique, department store, or dry cleaner in your area for a recommendation. If you're technologically inclined, try in-home tailoring services like Mend and zTailors. Here are a few things a tailor will be able to do to your garments:

Create your shape and size. Generally, you can hem or take a seam in as much as four inches; any more will throw the look of the garment off. And ask your tailor to follow the lines of your body. “If you're working with a dress or jacket, fit the shape of your back,” says Posen. “It's curved, not a straight line!”

Make more room. “People tend to think that you can only make stuff smaller, but you can make things a little bigger too,” says Young. “If a dress is hugging a bit, you can often find some room in the zipper or the side seam to let out.” You can also cut a slit or vent in a dress.

Find the right length. “With skinny pants, you can wear any heel height, since the hem should grace the top of the shoe,” says Young. For wide-leg pants, which should hit the floor, “buy two pairs and have one altered to wear with flats and one to wear with heels.” If you buy only one, hem it to work with the heel height you wear most often.

Streamline your silhouette. A tailor can close up pockets in a pair of pants,add hook-and-eye closures between gaping buttons on a shirt, or create darts under the bust or in the back of a top to create cleaner lines. If you always tuck in shirts, remove the bottom few buttons so they don't show under clothes.

Step Five: Consider Custom-Made

Still unsatisfied? Look into made-to- measure clothing, either from a tailor or via sites like eShakti and small boutiques on Etsy. It can be expensive (shirts start at around $100, and a full suit can run upwards of $1,500) but worth it, at least for frequently worn items. “Custom-made clothing is economical,” argues Posen. “If you take good care of them, your garments can last for a long time.”

Huffine’s made-to-measure must is a cocktail dress—like the Sophie Theal- let she wore to this year's Pirelli calendar launch. “I needed to wear a bra and I wanted to wear Spanx, so she designed around that,” she says. “In the end, the gown was something I knew I would be comfortable and feel like myself in.”

© James Ryang Lauren Chan and Zac Posen

And that, of course, is the point. The outfit I reach for when I want to feel like my best self? You guessed it: Posen's expertly tailored skirt suit. With it on, I stand taller, smile bigger, and behave more confidently. “We need to stop letting fashion make us uncomfortable,” says Huffine. “When something is tailored to fit you perfectly, it takes all worry away. Your garment isn't fighting against you—it's working with you.”

So the next time you're standing in the fitting room, remember: It's not you that needs to be altered. It's your clothes.