Primary things you need to consider and can be done you by only
> Documents, i.e. R.C Book, Insurance, Road Tax, Fitness Certificate(Yellow Board)
>Traffic Violations, these days its easy to find easily online, most states and cities have their online sites for showing details
Secondary Things that has to be checked by an Experienced Mechanic
>Get Engine Checked, how is its life and noise any minor or major repairs
>Is the engine original or same model as per the car year of manufacture
>Check the Engine number and chassis numbers if possible
>Its illegal as per RTO to change the engine without permission letter from them
Avoid these
>Vehicles older than 10 - 15 years in metros unless its an antique car
Other factors to consider
>Tyres- Branded Tyres or China Tyres(ask mechanic to list out the names), Bold or Rebuilt Tyres
>Body Line- minor and major scrathes
>Battery- Is the battery as of the requirements needed or its small or big
>Music System-better to be ignored is not there as it might cost 15, 000 to 20, 000 for the music system and speakers along with wiring
Things that you can avoid or use them during bargains
Tyres-China tyres(old owner has installed those to sell the car at any condition, as they are cheap)
Body Line minor dents