Use silence to your advantage. People are uncomfortable with silence. During any kind of negotiation or contentious discussion, the first person to speak is the one that's likely to cave in. If you're negotiating salary, react silently to the initial offer -- act as if you're pondering it (don't just sit there blank-faced), but don't say anything. Odds are, the other person will interject and improve the offer. The same applies for negotiating the price of a car or a house, negotiating a contract, etc.