You may already have a car that you would like to trade-in in order to lower the price of the car. A car trade-in can confuse negotiations, however, as it adds another element to what may already be very confusing car negotiations. You might also be able to get a better price if you sell the car in a separate deal to a private purchaser or to the dealership you bought the car from.
A good way to make sure you will get full value from your trade-in or sale is to present a very clean car to the potential purchaser.
If you are buying a used car, it is important to do a complete visual inspection to ensure that you are not looking at and wasting your time on a car that is a complete lemon. Just kicking the tires is not enough.
Look for signs of odometer tampering, or for signs the car has been in an accident and had bodywork is done.
Check for rust under the wheel well, and anywhere else on the car. Make sure the tires are still in good condition and will last until you can afford to replace them, at least. Sit in the car, and check for wear and tear on the upholstery, as well as for signs that someone smoked in the car.