Here's an easy formula to remember, one that will help you avoid sleepy audience NODS: Neutral, Open,Defined, and Strong. (And here's some essential information on how to use natural, strong gestures in public speaking.)
You should begin in a neutral position with hands at your sides (it may feel awkward at first, but it looks fine). That keeps you open to your audience, so that influence flows freely in both directions. Gesture sparingly, using defined or "clean" hand movements; and make them strong.Follow the NODS formula and your upper body movement will always support and amplify what you say.