Hi Naomi Try and look for one with plenty of history. You need paperwork from the year the car was manufactured till now. High milers do come with risks, so the lower the better obviously. Look for wear and tear, if the wear and tear is minimal then its had a good previous owner. Try and look through all the dealer polish to see how well the car has been looked after. I don't have any advice on common problems as I have never been an X5 owner. Also Welcome to the club :)