research > negotiation
when I bought my new car 2 years ago, after test driving at a couple dealerships and deciding on which car I wanted in the first place, I figured out the exact make/model/options I wanted, did research into the average paid price for that car by looking at Edmunds, KBB, and TrueCar, and figured out how much I wanted to pay for the car.
I walked into a dealership with that price in my head (contacting the salesman who helped me out with my test drive a couple weeks prior) and told the guy that if he met that price I'd buy a car today, or I'd go to another dealership if he couldn't.
he checked with his manager, confirmed, and we were off to signing paperwork while a couple in a cubicle across the aisle from me were still passing little slips of paper back and forth.
had he returned with a higher price offer, I would have just walked away.