This type of communication is as clear and sometimes clearer than language. Just as there are differences in language among cultures, so there are differences in the meaning of gestures. Here are some examples. Handshake should be firm and strong. Handshake is a light palm touch, with the fingers hardly bending.
People kiss the back of the hand they're shaking.
This indicates that there's a bird inside instead of a brain. Making a circular motion at the temple to indicate that things are spinning out of control in there. Making a circular motion in a counter-clockwise direction indicates that the person is crazy, but the same motion in a clockwise direction indicates that the person is intelligent. Middle finger thrust upward aggressively. First two fingers thrust upward aggressively with the palm of the hand facing the body.