Well I am not sure what you mean by you are good friends however you do not talk much. If you are friends that call each other, then I would try to call her sometime, invite her some where that is a little more relaxed than a party. It does not HAVE to be a date, then she won't feel so pressured (like when you are on a date). Maybe invite her out with some friends to dinner or a movie, just say something like me and blah blah blah are going to where ever and I was wondering if you wanted to come. Show her that you know how to have a good time, and make sure while you are there that you pay a lot of attention to her, aka talk to her. If you really like this girl, getting her out of a party setting to make moves is your best bet.

If you do not talk to her on the phone much I recommend talking to her friends that do talk to her on the phone and tell them to invite her... or tell her about something fun you guys are doing while you are at a party with her and get her number