Whatever makes you feel comfortable. If he is your legitimate friends as well as crush, just ask to talk to him for a sec, and tell him. Here are some ideas for what to say:
. "You know _____, your really cool. We should hang out some more."
. "______, I think you are really _____, ____, and _____."
. " I think we're more than just friends."
. "______, lately I've felt like we could be a great couple."
I know they sound awkward, but you just gotta go for it girl! If he says no, you'll probably be sad, but it really isn't that bad! And if he's negative, then he wasn't worth your time anyway! If you don't want anyone else to know, just ask him to keep it private.
