A lot depends on the starting point.
The best practical advice then is: try to maximize your expected payoff, which is the sum of all payoffs multiplied by probabilities.
There is no shortage of disputes.
A mediator is an impartial outsider who tries to aid the negotiators in their quest to find a compromise agreement.
Disputants often fare poorly when they each act greedily and deceptively.
The need is not for the creation of new analytical techniques specially designed for the negotiation process, but rather for the creative use of analytical thinking that exploits existing techniques.