Some clients like to see their (expensive) lawyers showing confidence and aggression, not least in public, and often in private too. Resist this, at least in private, because in private (with or without the mediator) the client needs to hear frankness and honesty from their lawyer (even if the advice seems unpalatable at the time).
Again in private, don't hide bad points behind good ones. You can be assertive with the good points, but be prepared to acknowledge the weak ones. And don't stubbornly stick to your guns if you know that the position has changed during the course of the negotiation. What your client really wants AND needs is a settlement on reasonable terms.
It may be difficult for a lawyer to back down from advice that has been maintained for the whole of the case, but it's better to do it in the mediation than to risk exposure and a lot of expense losing a court case.
You or your client can walk out at any time - but don't waste the opportunity to settle just for a grand gesture unless you really are prepared to go to trial over it.
Most mediations achieve a settlement, but of those that fail the principal reason is because one or both parties have not prepared their case fully. It is essential that you know your case well enough to be able to negotiate properly, you have necessary documents, and you have prepared realistic costs estimates.
Allow your client to speak, and to express emotions. If your client is likely to make a good witness in court, he or she will probably also impress the other parties in mediation, so make use of this point. Beware, however, the client who may become a 'hostage to fortune' or a gift to the other party as an open discovery opportunity.
Allow your client to explore options beyond the parties’ strict 'rights'. The elements of a settlement may be found in points that the court could not or would not hear. An apology is often one of the most important elements to a settlement.
Expressing a 'bottom line' early on is not particularly helpful. It is rarely, in fact, the point at which the parties do settle. Posturing and inflexibility will cause the mediation to take longer, and may cause an otherwise unnecessary 'climbdown' later on.
Don't be surprised if your client's attitude towards the other party changes dramatically from wanting 'justice' or 'victory' to a relatively amicable one with the possibility of a renewed trading relationship. This may take time, and the client may experience difficult emotions along the way. Don't be surprised, either, if their attitude does not 'soften'.
In a long running dispute the parties can become entrenched in their positions because they have stopped communicating. The mediation restores the dialogue and parties often realise that much of their anger and hostility has been caused by 'assuming' what the other party is thinking, saying or doing, 'rewriting history' or of not understanding why certain behaviour has arisen.