So look for body language in clusters of signals with common meanings. Once you understand body language, you can use your own voice and body to help make a sale. Take the handshake for example. A handshake can be soft, firm, brief, long, or even painful. The way you shake hands provides clues to your personality.
Aggressive people have firm handshakes.
People with low self esteem often have a limp handshake. Politicians typically shake your hand with their other hand covering the shake or holding your elbow. Domineering men often squeeze the hand of women during a greeting. The clever woman moves her index and little finger in toward her palm preventing a crushing handshake. This negates his dominant act and keeps her in equal control.