Tip 4: Impartiality
The mediator is often described as a "neutral". I am less sure about that term now.
Perhaps we are impartial, or more likely, "multi-partial". In other words, our role is to work hard to help all parties to understand what is going on and to reach an agreement if possible. Sometimes we work with those with whom we have worked before - as long as that is made clear in advance to others, who can choose whether or not they wish to proceed on that basis, we often find that knowing someone helps to move things along more quickly.