If you trade in your vehicle, you will probably not be paid the full value of your car. Selling it yourself is less convenient, but the best way to get the most for your money.

Dealerships make a lot of money on used cars. If you do trade your vehicle in, here's some advice from Edmunds.com on what you should know:

- Research the value of your car on Web sites such as www.Edmunds.com, www.NadaGuides.com or Kelley Blue Book, at www.kbb.com. Knowledge is critical.

- Clean out the car thoroughly because you'll want to present the vehicle in its best possible light.

- Change the oil and oil filter. The dealer may check the dipstick to make sure the car's engine has been cared for properly.

- Consider repairing anything that might be damaged, since the value of your car is reduced with every flaw. If you don't do the repairs, you should have an estimate on how much the repairs will cost so you can negotiate a fair value for your trade in.

- If you owe money on the trade-in, make sure you call the bank for the exact payoff amount. Accuracy is vital in negotiations. If you still owe more on car payments than it is worth, consider postponing your new-car purchase.

- When you have agreed on a price for your trade-in, focus on the purchase price of the car you are buying. When you have agreed on that price, the trade-in should be applied as part of - or all of - your down payment. Keeping these figures separate will help you get the full value of your trade-in.