What skills make a person an effective negotiator of contracts?

Good listener, predictive, have knowledge about the project and actual market, experience, commuincation skills

a) Clear compass in his/her mind: well set targets and envisioning a roadmap b) empathy: listening to the other parties with genuine interest c) balanced: preference for a win-win agreement better than winning5-0 the match.
d) superb communication skills, if possible ability to laugh or find humour in difficult / stresful circumsatances e) resilient