Not so much make/model advice as general advice. All my examples are for the UK, but it's roughly similar where-ever I guess.
Stay away from anything over 50k miles (that's 80,000 kilometers) as by that stage they're well out of warrenty and free service periods, so the chances are various tightarse owners have not fixed problems or had the yearly service done. This tends to lead to a car with bits that fall off. The exception is if you can find one with a complete service history - then it's worth a glance, but read around on common faults and problems with that model version. It's well worth going to
www.parkers.co.uk or equivilant, finding the model you're looking at and stumping up £2.50 or whatever it is to get their handy dandy PDF model guide which tells you all the common faults and the signs to look for to tell if they're there or not. Sites such as Parkers can also be a handy guide to see what sort of cars are available in your price range.
Basicly, find a make and model (or maybe a couple) that looks like it's right for you. Go around and find several examples to physically look at while "pretending" to be interested in buying - this lets you see the range of what you can expect to get (ie. added spec options etc) for what money, and what sort of condition you can expect to find the vehicle in.
Any rust is a bad sign as it indicates previous owners haven't really cared for the car. A careful owner would deal with chips and scratches before rust had a chance to set in.
For god's sake don't buy the first thing you see, always get a good idea of what's out there. Private second hand sales might move fast, but if you miss something another will be along shortly. Dealer sales tend to hang around longer anyway, so you can take your time.
And always be a cynic. If it looks too good to be true, 99% of the time that's because it is and you've just bought a cut and shut.