All it takes is one "hey there... I'm (insert name here) what's your name... ohh wow those look heavy, can I carry your books for you" If she lets you then not only have you introduced yourself but you are walking her to class and having a conversation on the way.
That's just one method of making a first contact / impression.
Back in my day that was called being a gentleman. It also shows her that you care about her at least enough to try to get to know her.
But then again times are changing. A simple hello might work wonders as well.
It only takes a few words to introduce yourself to her and try to start a conversation. So even if you see her only once a day there's your opportunity.
Even if you end up in the "friend zone" as someone else put it... when you're hanging out with her... well other guys will so envy you if she's a really pretty one. In these times you can never have to many friends, so make as many as you can. I have to think that the better relationships are built on friendship first. I was friends with my wife first.. our relationship has had some MAJOR problems but the foundation of friendship first saw us through those problems.
Even if you see her just once a day all you need is that once shot, but don't think of it as a shot just think of it as an opportunity, and be yourself.. even if you're nervous she might find that cute for all you know.
I play bass guitar in a band, and I get 20 year old girls all the time trying to flirt with me. The ones I really get flattered by are the ones that are shy.. maybe it's because I know they're the ones that are most likely wanting to get to know me as a person and not just some guy that plays in a rock and roll band... I always have to tell them "sorry I'm married, but I'm very pleased such a beautiful woman such as yourself thinks I'm worthy of your attention. I'm happy to have your company tonight between sets, let me introduce you to the rest of the band... can I buy you a drink or something.. I would love to see you again here's where we play our next show.. etc..."
I mean it's all about just getting out there and making contact. Just be honest with yourself and her.