If you're meeting her in an hour, then you need to flirt with her and build up excitement for the event. Mess around with her and joke with her. For example, you could say something like "T-Minus (however many minutes) until the big event of the night!".
When you meet up with her, do the same with a slight twist. In group situations, if the friends like you, then they will help you out with the target. Thus, it is essential to be a good host and to get the friends involved and having fun. Of course the main goal is getting her, but the friends come first for tonight. If things go well, then you will be seeing her or one of her friends again.
"There is no better than adversity. Every defeat, every heartbreak, every loss, contains its own seed, its own lesson on how to improve your performance the next time." - Malcolm X