My colleague, former judge and prominent mediator/ arbitrator Abraham Gafni gives his students well-known advice: to complete a negotiation successfully, you must provide satisfaction on three fronts.
Procedural satisfaction. Everyone believes that the process has followed a fair, agreed-upon procedure.
Substantive satisfaction. Although participants may not get all that they want, they can agree on the compromised result.
Psychological satisfaction. Participants must feel that the negotiation was acceptable, fair, and, therefore they are comfortable with the process and with the result.