Well, it seems youve got quite the situation man. All that is important is to be yourself. No matter if shes a prep, goth, or any other of the social classes. Go into the situation thinking you have nothing to lose. Just be friends the first time you guys hang out, and if you sense something move in. Also, look for any of the signs that girls are attracted to you. If she plays with something, like a necklace or her hair, it means she is interested, thats a definate sign if she does it alot. Be aware of her body language, if she moves closer move away, it drives women crazy. She might think that she might be doing something wrong, and therefore shell try even harder to get closer to you.
But of course this is from my personal experience, so if this doesnt happen to you dont worry. Just be cool about the situation, and have fun. Theres nothing to lose if you just gain a friend.