Assume some things will go wrong or break once you take the car. There is always issues, and best to be prepared.
Make sure owner is not a dickhead, obviously. Check condition of tyres and things when first inspection, then compare it to when you go to pick it up (if they did monster skids and drift sesh before handing over the keys. happened to me).
But yeah, unless its totally f**ked or a piece of shit, you should come out on top.