Speak calmly and clearly in a manner that makes it seem like you are in control, with total confidence. If you get nervous, slow down. Maintain frequent eye contact with the entire audience. Look down at your notes, not to read the presentation but to remind yourself where you are. Keep a glass of water at the podium.
Anxiety can create an instant dry mouth.
Also, don't be afraid to take a moment to catch your breath. The audience will wait. A long pause is also a good technique to regain the audience's attention. Don't think about the delivery of the presentation as you are delivering it. Ignore that little voice inside you that wants to criticize the presentation as you're speaking.