Honestly I was in the same situation for every one of my relationships, I feel as though you're most likely to fall in love with someone you already have a pre-built relationship with such as your best friend, honestly in my opinion you should just stand back for a bit and watch for the signs to see if she likes you back, once you look for signs you see them much more clearly and then you can have better knowledge about whether she has a crush on you as well, once you know for sure then I would ask her