Your mother probably taught you that it's rude to stare. But when you negotiate a business deal, close observation of your opponent makes sense.

By inspecting your opponent's every physical move, you can often determine whether he or she is holding something back or not telling the truth. The key is not to stare so much that you make your opponent uncomfortable, but to be aware of his or her movements through casual glances and friendly eye contact. It will almost certainly give you an edge.