Respect.
Depends on the type of party. Buuz = Sit next to her and ease your way into one of her conversations with someone else.. Then find common ground and try to get her somewhere secluded.
Clean party = Be near her, but next to her would probably weird her out a little.. Ease your way into a conversation she's in after she's comfortable with her environment.. Then try to stay in. Next find common ground.. Then try to take her on a walk or seperate her from any group she's in somehow.. But not in an obvious manner
Pretty much the same thing, but clean party means its ten times harder and requires a ton more effort.
Of course, it's a lot easier if the chemistry is just there and you meet the "right" girl. When you actually try it's on your mind almost the whole time.. Possible, but harder nonetheless.