You can learn a lot about the power of hand gestures by watching Ben Vereen and the entire cast from the Broadway musical PIPPIN. The timeless Bob Fosse choreography offers a variety of expressions throughout the entire clip. The body language says it all.
If you want to see specific comments, The Visual Critic analyzes this video, highlighting some of the effective presentation techniques used by Ben Vereen and the rest of the cast in the opening number Magic to Do.