Know what you want before you step foot in a dealership. You are going to be dealing with professional salespeople, so have your mind made up about what you are willing to pay, what you effuel reviews want and what you are not interested in. That will make it less likely for them to sway you.
If you are going to be purchasing a used car, one of the top things you should be looking at is the mileage of the car. As nice as a car may be, if it has 150,000 miles on it already, you probably will not get much use out of it.
When buying a used car, be very careful about how clean the car is. Many car salespeople have professional cleaners who can make a piece of junk look brand new. Always get the car checked by a mechanic. Even if it looks fantastic, a mechanic will be able to spot any major issues.