Getting to Yes : Negotiating Agreement Without Giving In by Roger Fisher and William Ury
Basic concepts (also Chapters 1-5):
Don't Bargain Over Positions( car buying can be a different story) -- aka DontHaggleJustWalk
Separate the People from the Problem -- DontPersonalize?
Focus on Interests, Not Positions -- A classic example of this is the Camp David Peace Accord. Both Egypt and Israel wanted the Sinai, but for very different reasons. Egypt wanted sovereignty, Israel wanted security. A formula was worked out where the territory was handed over to Egypt, and Egypt agreed not to position offensive weapons there. (U.S. spy satellites provide an ongoing guarantee that Egypt won't backslide.)