Nervousness is pretty normal during public speaking. What I do is I try my best to focus on what I'm saying and how I'm saying it. Don't focus so much on the fact you're speaking and at any moment you could make a mistake that would ruin your life forever! Focus on what you're saying and try to keep those words coming. Forget about those in front of you; zone out into the topic if you have to.
I like to use visual displays. It does not matter if it is a powerpoint presentation, a poster board, or a handout, but I make sure the audience has something to look at besides me. Plus it gives you, as the speaker, something to refer to in order to keep you focused.