1.  Check the milege travelled vs the year of Mfg.  If it has run 10 k per year it is ok.  Some milo meters are tampered though.
2. 

Check the engine heating after test drive.  If it is unbearably hot then it is likely to have clocked more milege.
3.  Check the steering veering, while you take your hands off the steering.  If it veers it requires urgent suspension work.
4.  If there is steering rattle of noise then your assembly needs change of bearing.
5.  Clutch assembly generally needs a change.
6.  Check whether self driven car or company vehicle.
7.  Wiring under the bonnet whether tapes are applied to join wires.
8.  AC effectiveness.
9. Braking effectiveness.
10.Smell of the oil.
11.Smoke levels.

For a trained person the feel of driving comfort will give away the condition of the vehicle.  Please remember any vehicle after 80 km will come up for maintainence repairs and major haul.  An ideal bet is to pick up vehicle which has run below 30 km and sell it when it touch 1 lakh km.