The question I get asked most often about body language is, "What do I do with my hands?"  My answer, when there's a video screen handy, is to show a clip of Leo Buscaglia speaking.  Leo was a wonderful public speaker on the subject of relationships (he wrote a bestseller back in the day called something like Love 101) and he gestured beautifully with his hands.  In fact, his hands virtually told the whole story; you can just about get the speech from his gestures if you turn the sound off. 

The point is not that everyone can learn to gesture like Leo, but that you've got a much wider range of expressive options that you perhaps realize.  Most people hold their elbows close in to their sides protectively and wave their hands from the elbows on down.  I call this the 'Penguin Gesture', and it's not very expressive.  It signals to the audience that you're nervous, or feeling exposed, or shy. 

What I've noticed is that when someone gestures like this for a whole speech, they tend to stand in one place, and gesture less with the face as well.  In other words, the whole 'second conversation' of body language shuts down.  The result?  Slow-motion panic for the speaker and boredom for the audience. 

Don't get trapped by limiting your hands to a tiny retinue of gestures.  Gesture from the shoulder, using the whole arm.  Talk with your hands, to the extent that you can do it tactfully and appropriately for who you are.

And one more thing.  Keep your gestures open.  Don't fold your hands in front of your chest, or crotch, or put them behind your back.  All of these are defensive gestures and will not inspire trust with your audience.  Keep your gestures open and reaching toward the audience.

Think Leo, not penguin.