How can I negotiate for the best purchase price?

First, apply for pre-approval.  With pre-approval, you will know exactly how much car you can afford.  Consider using the Check In Hand program, which allows you to shop like a cash buyer.

Second, don’t negotiate on any car until you’ve had a chance to run an Edmunds true market value assessment on its make, model, year, and mileage. Research its Kelley Blue Book value too, so you can walk in fully informed. Refuse to accept any price above the car’s true value.

Be aware of the tricks of the trade. Dealers may try to tire you out by making you wait, confuse the issue by introducing figures you’re not familiar with, or ask you questions you’re not ready to answer. Take control of the conversation. If you’re not sure of what’s going on, don’t hesitate to go home. You can always come back the next day to try it again — on your terms.