1. Remember this is all about winning - and nothing to do with whether or not people like you. So be prepared with as many clever arguments as possible. However tenuous the point, it's very important to be able to contradict everything the opposition says to you on principle.
2. Determination is better than flexibility, every time. Whatever your strategy, stick to it no matter what.
3. Don't give away any information of any description. And don't ask any questions. You're in there to tell them what they ought to accept: like it or lump it.

However tenuous the point, it's very important to be able to contradict everything the opposition says to you on principle.

1. Tell them yours is a better deal by far than they'd get anywhere else, so they'd better hurry up and say yes while you're still in a good mood. Wagging a finger across the table at the same time will make your position even clearer.

1. Never talk about 'I' or 'we'. Use the passive or second person ('you'), e.g. 'It's obvious to anyone', or 'Surely you must see that...' Be sure to avoid saying things like: 'I'd like to explain' or 'How can we move this forward?'
Be constantly suspicious. Whatever they say, they're bound to be lying.
2. If they say something you think is unfair, protest loudly and emotionally.
3. Never allow silence in the room. When you name your price, carry on talking until they say yes.
4. If you're part of a team of negotiators, decide who's the leader and let that person do all the talking. The rest are only there to bolster up the show of power on your side.
5. Remember that some things are just non-negotiable.