Tip: Don't buy anything from anyone who smiles slyly, rubs his hands together and says "eeeeexcellent".
Hey, it's valid advice! :D
Apart from that, check the mile counter and make sure all the numbers are aligned. If they aren't it could be a sign that they have "clocked" it. (A special tool that "rewinds" the miles so it looks like it's done less).
If you are buying from a reputable 2nd hand dealer this shouldn't be a problem.
Also, again if you buy from an actual 2nd hand dealer, the car should come with at least a 3 month guarantee. In the first 2 months I would pay special attention to everything your car does, what sounds it makes etc and put it through its paces, right down to the brakes. I've had a bad experience before where I bought one from a dealer and the handbrake wouldn't work properly. Took it back twice and the guy said it was fine and all I had to do was pull the lever up more. Took it to a mate who isn't even a mechanic and he spotted it straight away. The handbrake pads were down to the metal. By then, the dealer had fobbed me off until I had gone over the 3 month mark so that he wouldn't have to pay for it.
