Crikey loads of stuff...
- The normal serivce books tallys up with service history - dates and mileage
- Any accident damage signs
- Wear to disks/pads and tyres
- Exhaust prone to rattles
- Suspenion prone to rattles and squeaks
- Ensure all servcing done etc.
- Any broken bits, kerbed wheels - tracking/suspension probs
- Make sure the engine isnt worn when you turn up to view - tell-tale sign its been pre-warmed. To counter act this, turn up early for viewing
TBH - most normal stuff plus that above mate and you should be ok.
Just look for signs of stuff that arent rght. Any worries, make a list in your head, write them on here tomorrow and tell the owner of the car "youll have a think about it".
Cover your arse and dont get sucked into buying the first car you see.