Lingerie is the most exciting part of any wardrobe for me, but it can also be the most complicated to get right. It is always frustrating to find the cutest little lingerie set only to discover it doesn't fit, the straps are too thick, the band is too wide, and everything just looks.. wrong, wrong, wrong! Over time I have discovered what styles work for me, which ones I should avoid, and all the terrible mistakes I had been making.
1. Size. Measure yourself (or get someone else to)
2. Technique. Use the proper fitting technique
3. Identify. Identify common problems (bulging, movement, gaps, wrinkles, and discomfort) and avoid them
4. Style. Discover what styles work for you, they need to be comfortable and flattering
5. Shopping. Be prepared to spend a lot of time (and maybe even money) to find the perfect fit
The best tip I ever learned was 'the size of the cup varies with the band size.' If you want to try a smaller band size, you need to compensate by choosing a larger cup size or vice versa. For example, if you find the band on a 36B bra is too loose try a 34C instead or if the 34B bra is too tight, try a 36A.
Sizing is just a starting point and will vary between brands, remember every womans' body is different but lingerie is mass produced; if a design doesn't suit you this doesn't mean your body is the problem. Remember you can wear something else but also don't forget you can easily modify lingerie by adjusting the straps, adding strap padding, or even fitting band extenders.