Would you negotiate for a used car without preparation? Not if you're smart.
If you don't have the stomach for negotiating, buy your used cars at CarMax.
Never go one-on-one with a car salesman unless you have prepared.
You must know what never to say. Then don't say it.
The same is true of job negotiations. The salary you will receive and the time
you will be asked to commit to (after they've got you by the throat) will
depend on what you got for yourself in the original negotiation.
Never, ever go into a job negotiation unprepared. You will have your head handed to you if you do.
Go here first: http://www.asktheheadhunter.com/