Check the seal at the top of the windshield, make sure the top sits flush, check the top pump, make sure it goes up and down and check the seal around the back window. If the seal around the back window is no good, it can't be fixed, only replaced which is around $1500. Other than that stuff for the top, just check the usual places like the radiator support for possible crash repairs and so on.
You'll also know a little history about the car by simply checking if the car comes with the boot to cover the top while it's down and the carrying case for the boot when it's not in use. If those two things come with the car, it was well taken care of, if not, it might have been taken care of but I would have my doubts.