Just walk around it and kick the two front tyres - job done
I was going to make the same joke
Dont expect perfection, but roughly:
Start with the bodywork, make sure all the panels have good gaps which are the same size all the way down. Make sure there's no deep scratches which are down to the metal and that stone chips have been kept under control. Check for rust over the car, under the arches etc and any known problem places for the particular car.
Interior, check its all in tact and everything works, especially all the electrics. You cant expect too much at this price but you just want something thats clean and in one piece. Make sure the handbrake holds the car well and doesnt need to be pulled up really high to work.
Make sure the car's cold when you get there so you can make sure it runs properly when cold, starts properly and gets up to temperature and stays there. Start it when standing outside the car to look for any big puffs of smoke - do the same by revving it. Blue smoke for oil, white for water and black for too much fuel.
Get under the car and make sure there's no obvious damage to the floorpan and that the exhaust is in tact and secure. You'll also be able to spot any oil leaks while youre down there. Check all the tyres are wearing evenly and have decent tread.
Under the bonnet, check all the fluids are at the correct levels. Check for "mayonnaise" in the oil filler cap or dirty/oily water - either generally means the head gasket has failed. Make sure things like the HT leads are in good condition, there's no oil in unusual places etc. Make sure the battery is in good knick too. Be suspicious of an engine bay thats too clean, it may have been steam cleaned - this can be to cover up a biger problem and can cause problems with steam in the electrics.
Test drive it and make sure it feels right - the clutch shouldnt be too heavy and should bit in the middle of the pedal. The brake pedal should be firm not have too much travel. The gearbox shouldnt be "sloppy" and there shouldnt be any play in the steering wheel. Find a quiet stretch of road, loosen your grip on the wheel and brake hard from about 30 - make sure it doesnt pull to one side. If the car has ABS an emergency style stop from 30 should make it kick in, if it doesnt you the brakes should be effective enough to lock the wheels. Again, driving about 30, put it into 5th, press the clutch, rev the engine quite high and dump the clutch - this will show you if the clutch is slipping. Listen for any odd noises like clunking, knocking, squealing etc.
Thats about all I can think of at the moment but theres probably a lot more