Hands Up!

To maintain some control over your gestures, be conscious of your gesturing, and do so only to emphasize key points or ideas. In doing this, it is important to make definite and deliberate hand movements. When you speak, keep your hands in your lap or relaxed at your sides, with your fingers relaxed. Doing this tends to relax the rest of your body.
Of course, this doesn't mean you should sit totally motionless. But the motions you do use should be relaxed.
When you use both your hands and arms in a more fluid and open fashion, you are perceived as being warmer and more approachable.
If you notice that you are using your hands too frequently when you speak, try to be mindful and stop or reduce your hand movements. Being conscious of doing something to excess can often help you modify that behavior.
If you still don't know what to do with your hands, adopt the hand posture of the royals, who tend to keep their hands clasped in back of them when they stand or walk. Doing this often suggests to others a sense of security, control, and self-assuredness.