Check insurance is a first thing I would do , weigh up what you want from the car , if you don't mind me asking what's your budget ? Do you want a classic or newage ?
Do you want to modify it performance wise ?
One thing I always do is google the number plate , might thro up some results on previous owners , good or bad !
One my friends wanted a rb320 then googled imaged it to show us in the pub one night what he was after , turned out was the press car so had been abused from cold at a early age