Some tips:

Remember that you have the upper hand. You're the one whose business the salesperson wants.

Think about this old adage from the world of negotiations: "Whoever speaks next, loses."

Don't offer any more information about yourself than you have to. The more a salesperson knows, the more that person can tailor a strategy to you.

Rein in any enthusiasm. No drooling in the showroom. Don't let the salesperson see your hand trembling in excitement as you caress a fender. If you must buy a car this day or this week, don't reveal that. Any urgency on your part transfers some bargaining power to the salesperson.

Understand that, if you're talking to a salesperson on the phone, he or she desperately wants to get you into the showroom. If you're in the showroom, that salesperson desperately wants to sell you a car right then and there. If you're ready to buy a particular car, he or she desperately wants to switch you to a more expensive car, or at least get you to pay as much as possible for whatever car you buy.

Be prepared. Do a lot of reading and researching so you're not thrown for a loop if you're suddenly offered an extended warranty or some feature you don't know much about. Better still, by doing a lot of reading, you'll be prepared for the many ways that salespeople will try to manipulate you into buying something you don't want or paying more than you need to.

Don't negotiate alone. Take some friends or relatives with you.