1. Don't pay attention to the size on the tag.
I think this is where a lot of us get in trouble. We have this idea in our heads of what our size is, and this can come in handy when we're browsing through the racks, but when it comes to actually figuring out what size is going to fit us best, much more scrutiny needs to go into the matter. One thing that helped me realize this was thrifting. When you're thrifting, you're often dealing with clothing from hundreds of different brands (all with differing sizing standards) and a variety of different decades. For example, if you try on a medium item that is vintage it's likely it's more like a small or extra small. This taught me to ignore the size on the tag and instead look at it objectively to see if it would fit. And then, trying something on is always the best method to figure out the fit of an item. I've pulled many a piece from the racks thinking it would be perfect only to discover it fits totally wonky!
When it comes to shopping online, this also applies, though you don't have the luxury of trying something on (though if the shop has a good return policy, you can always return the item if it doesn't fit well, or exchange it for a size up/down if it's just too big or small). One thing I've really gotten into the habit of is checking the size guide. This will usually give you measurements for bust, waist and hips typical to their sizing. Make sure you know what your current measurements are!
Something that ModCloth does is that they have an area with each product where people who have purchased the item can review it. They can include their measurements, what size they bought, and then comment on the quality or how it fit. I always check these reviews before I buy something, simply because it is so helpful to figure out what size I need to get, or if the item is even going to look right on me. People can even upload photos of themselves wearing the item so you can see visually how it fit them. I love this feature and have found it so helpful that I've gone back and reviewed the items I've bought so I can help others figure out if they'll work well on them. Features like that are on a few shopping sites I've found online, and I always think they're helpful! When shopping online, try to see if the shop you're looking at has a similar feature.
2. Realize that your top and bottom may be different sizes
This is especially important for those with a more "pear" or "inverted triangle" type body shapes, like myself. My body shape is more wide at my hips than my shoulders/bust, so I always need to make sure that things I buy have enough room in the hips. If I buy a dress that is fitted to my bust, it might be too tight around my hips. Because of this, I'll usually look for items that have a free-hip, or a fabric which stretches so that it'll fit up top, but have enough room for my hips. Figure out what your body shape is and make sure you choose pieces that fit you!
3. Utilize tailors
I am short. Because of this, almost anything full length, like pants, dresses or skirts, will usually drag along the ground. There are many times you'll try something on and it will be perfect except for one small fit issue, and for those decide if it's worth the time and money to take it to a tailor. Sometimes it can be less of a hassle to just get something tailored to fit you, rather than spend hours and hours trying to find an item which fits you just right. The truth is, there may not be a brand out there which designs for your shape, and you'll have to take things into your own hands. Find something that fits great everywhere else, and then take the garment to a tailor and have them fix the spots that aren't fitting well. Or, if you're a super awesome seamstress, you can try tailoring stuff at home!
4. Wear what makes you feel confident
In high school, I didn't have the confidence to wear things that were too far out of my typical daily style (flare jeans, thrifted little boys' tees, skater shoes). In retrospect, it would've been great to have been able to explore more of my style back then, but because I didn't have the confidence, wearing new and different things would have just made me felt uncomfortable and self-conscious. In the end, what really pulls off an outfit is the confidence of the person wearing it. You may be wearing a fabulous outfit, but if you don't feel confident in it, you probably won't look as fabulous as you'd hope.
5. Invest in good undergarments
First off, I think this is mainly for comfort's sake. If I'm wearing an itchy bra or undies which ride up all day... I'm not a happy camper and it's constantly distracting. Who wants to be picking a wedgie all day? Not me.
Another thing that a good foundation does, is make your clothing fit well! You want undergarments that don't show or bunch or pinch, so that your awesome outfit isn't upstaged by weird panty lines or bra straps. Plus, apparently according to Mandy, a bra fitting can change your life.
