I have always likened buying a used car to traversing some kind of assault course, laden with all manner of traps and pratfalls ready to catch the unsuspecting victim out. A car sat on a dealer's forecourt may look absolutely divine and enticing to the potential buyer. However, a closer inspection under the bonnet may reveal a multitude of problems that would cause many headaches in the months to come.

With this in mind it is definitely worth only visiting reputable used car dealerships, as they will offer you assurances of quality, such as 3 month mechanical guarantees and suchlike. The trick to ensuring you get the best quality used car is to do your car shopping with a series of questions in mind.
 
The first of these questions is to ask about the vehicle you are interested in with reference to service history. If a vehicle comes with a full, comprehensive and up to date service history, it is highly likely that the vehicle has been looked after and you shouldn't get much trouble out of it. The second question is to check if the vehicle has been involved in any serious accidents that are likely to affect performance later in the ownership of the vehicle.
 
When I was faced with the task of buying a used car, I looked specifically at Used Audi models, as a manufacturer of Audi's ilk and reputation can be relied upon much more than many of the competition. It may cost slightly more, but the investment will pay off over time.