The success of your negotiations will depend in large part on the quality of your preparation. We often make the mistake of thinking that we don't have enough time to spend on preparing for negotiations. Our research indicates that the primary contributor to eliminating misunderstandings & shortening the negotiation cycle - therefore saving you time - is the quality of your preparation.
You will most definitely benefit significantly from your upfront investment in preparation - try to spend at least as much time preparing for negotiations as you expect to be involved in actual negotiation - ideally spend as much as 3 times more time in preparation as you expect to be involved in actual negotiation.