Mr. Cohen outlined a framework for collaborative negotiating based on the work of Roger Fisher. To avoid getting stuck in the mindset of negotiating as a competitive game, Moshe Cohen recommends that you listen to what the other person is saying, then talk about the assumptions being made. There is much to be gained from negotiating, if you turn it into a collaborative game. When negotiating is based on interests rather than positions, mutual gains result.
Positions are what people say they want in a negotiation.
Find out what is driving the other side. Ask about their interests. Ask why their proposed solution works or what problem they are trying to solve. Tell the other side your interests. If you need something, they won't know unless you tell them.