I read a lot of reviews on Amazon for this sports bra, many of which suggested to go up a cup and band size. Normally being a 32E in sports bras, I went for the 34F, which arrived today. The reviews weren't right for me! It's too big in the back and the cup!! So, I think everyone is gonna be different with the sizing on this. In a normal bra, I'm a 30E, so I'm gonna have to return and opt for a 32E, which I think will be about right (judging by the one I tried today). I really have struggled to get a good sports bra for playing competitive tennis that is supportive and gives a good shape, and snug but not over-tight on the band. I have a normal one so wanted a racer-back style. This seemed like the perfect choice, BUT will have to see if the normal-sized one fits!!
** UPDATE **
Mainly updating the review as I know just how hard it is to get a sports bra that fits well!! I got the 30E today, and it fits perfectly! Again, bearing in mind that I'm a 30E in a standard bra, the 32E in this one fits snug but not too tight on the band, and the cups cover well with no spillage around the edges!! I basically just open the clasps, pop it over my head, then fasten it behind my back. This won't be easy for everyone if you're not very flexible...
Also, I have found the reviews saying the band/cup comes up small completely wrong for me. If you don't try one on in the shops first, then I'd say go for your usual cup size but go one band size up. That worked for me!! Now I've got the sizing right, I love it!!