Stay open-minded about how the dispute may be resolved. New ideas that are worth considering might emerge during the session.
Be flexible and give yourself plenty of room to negotiate. Don't back yourself into a corner by issuing ultimatums - new information may come to light that will make you want to change your position.
Be willing to give and take - you will be expecting the other party to compromise to meet your needs, be prepared to do the same.
Stay calm and focussed. Show respect for the other party and the mediator when you communicate.