2. Be nice. They're more likely to concede if they like you.
3. Don't be assertive. Be calm and cool, act like you know what you want. Assertion encourages them to push back.
4. Say no without saying no. Something like "I really wish I could do that, but it doesn't work for me."
5. Label every fear they have, and label all their advantages. Sometimes they point out an advantage of their product (or the job) in hopes of pushing you back.
6. Instead of proposing solutions, ask for their opinions. It exhausts them mentally, and it puts them in control.
7. Try to be yourself, and don't try to mimic other people's negotiating strategies. Some people are more accommodating, some people are more stern, some are rigid. That's all fine. Learn what you are like and make use of your strengths.
:)
Know what they want (listen; try to see their perspective). Do you have it?
Remember that leaving money on the table might seem a sub-optimal negotiation, but think of it as an investment in the relationship - for if you ever deal with this person again (which you will).
Getting to yes.
The mind and heart of the negotiator.
Both were required texts for my college class on negotiating and conflict management.
Also, understand your BATNA and get as much data as possible. Good information facilitates a win/win scenario.
E.g. 3 job offers rather than 1.
E.g. pay raise, but if they have no budget how about an extra week of leave.
More time = more options
No time = desperation