tips for improving your public speaking will make even a garden-variety speaker into a real
Do your homework. Nobody can give a good presentation without putting in some serious time preparing remarks. It's always a good idea to try out your presentation on your professor (or TA) before giving it in class. Office hours work well for this.
Play the parts. Good presentations are structured in sections. Many presentations need only two or three main points.
Do a dry run. It's always good to do a run-through (or even a couple of run-throughs) the night before the presentation. This can help with both your timing and your manner of presentation. Be sure to make mental notes if you went on too long or got nervous or stuck. Some people find it useful to have a friend pretend to be the audience: He or she can build up your confidence and maybe even ask a question or two.
Look presentable. No need to wear a suit, but it's hard for people to take a presentation seriously when you look like someone who just rolled out of bed.