At the beginning of negotiations, establish (in your mind) the lowest acceptable offer you'll take. That way, you have a sense for how far you can go before you start cutting into profit margins, production capacity or whatever benchmark you're using. As the negotiations proceed, you know where you are at all times, and that sense of security can give you greater confidence.
Establishing the lowest acceptable alternative in advance does something else: It keeps you in a win-win frame of mind because you don't have to worry about losing. As long as you know the point at which you will walk away (and stick to it), you can't lose anything.
Excerpted from Creative Selling: Boost your B2B sales