Start with the basics. Check for rust, especially around the sills and arches. You'll need to keep your eyes and ears open on the test drive - check for signs of overheating and any knocks and rattles from the suspension. Cooling, ECU and electrical issues can affect most X-types. Check everything works - lights, wipers, fans, air-con... everything. Failing transfer boxes are a common weak spot - listen out for whining and look for leaks. You can check the car's MoT history here: www.gov.uk/check-mot-history