I feel like, as in many things, you learn to give presentations by giving presentations. Offer to give the same talk to your college's ACM or LUG groups a coup

I feel like, as in many things, you learn to give presentations by giving presentations. Offer to give the same talk to your college's ACM or LUG groups a couple weeks before. To me questions are always the meat of a presentation -- getting good questions means that you succeeded in getting people thinking. The most important thing is to know what you're talking about (a surprising number of presenters / politicians / whatever don't). If you know your topic reasonably well, you answer a question as far as you can and if it goes beyond what you know it's ok to say, "I don't know." You can use that too to sidestep questions that aren't really on topic and take away from relevant questions.