Find something in common to talk about with her. You might try:

1. a teacher (did you see Mr. Whoever's tie today? isn't it loud?)
2. a class (did you get the assignment? or have you ever taken spanish?)
3. how was your weekend? what did you do?
4. the weather: it is so cold out! but I can't wait to go snowboarding! do you ski or anything in the winter?
5. I like that color on you, by the way give a compliment but don't be like "you are so gorgeous" b/c it's too forward.

Good luck. Remember, you only get what you ask for. So don't be afraid to ask!!

If things go well talking with her, and you're still into her, then don't be shy - ask if she wants to hang out and grab a coffee over the weekend or something.