Have a good read round this forum.
Thats what I did, even though I did not register or post until I had owned it for six months and wanted to know how to service it.....
In no particular order:
The wheels are very soft and expensive to replace. They may not be round any more. If just in poor condition, they can be refurbed at approx £70. This will make them look nice, but will NOT make them round again. A NEW wheel is approx £300. There are plenty of second hand ones about, but mostly they are, err, very second hand...
The cam belt has to be changed every 60,000 miles, as well as the tappets. If the car is over this milage, check they have been done. If the car is under this milage, factor it into your haggling.
It needs an oil change every 6,000 miles, even though the service indicator wont show this. Check its been done.
Put the lights on with the engine off and listen to each head light. If you can hear the height adjustment motor running constantly, you need to replace the light unit, which will involve a few hours of labour as the front body work has to be replaced.
Sat Nav Discs are expensive. If the mapping is out of date, you need to buy a new disc.
Brake discs and pads are expensive. When were they last changed? You can get some idea of their condition by looking through the wheels.
Other than that, only what you would expect for 5 to 7 year old car.
Check EVERYTHING electrical works (including the AC).
Check it drives & stops striaght. Check the clutch is not slipping.
Look underneath for corrosion, evidence of damage, or evidence of previous repairs. While you are under there, check for fluid leaks.
Look at tyre condition. Even wear?
Does the engine smoke, check for mayo in the oil filler or the expansion tank?
Do all the doors open & shut correctly. Even panel gaps?
I am quite new to Smarts, so I am sure someone will be along in a minute to add everything I have missed or dont know about.
There is one listed for sale here that looks like a bargin, if you are in the right part of the world.