Always know what the car is worth before you go in. Get price reports from KBB and Edmunds. Find out what other people in the area have paid for a similar mileaged car. Inspect the car to see what kind of condition it is in, test everything on the test drive.

Know your credit score and what kind of rate you could get with a credit union. Price isn't the only thing you have to negotiate...you can also get them to drop the interest rate. They're going to try and get you for a high rate first, because they'll make more money if you finance through them.

When you start to negotiate, they're going to ask how much you want to put down, and what you want your monthly payment to look like. If you know how much you want to spend for the car, and what kind of rate you can qualify for...you can use an online payment calculator to estimate your monthly payment. Don't just arbitrarily say a number that you can't go over...they'll use that to their advantage.

Just be smart. If they want too much for the car, don't be afraid to leave. They will either come close to your price, or you can find one elsewhere.