Take close look at the brake disc's and foot pedals.
If you know what to look for it will give you a fair indication (not 100% obviously) on the vehicles real mileage against what the seller is suggesting it is.
Run a finger across and to the edge of the brake discs, a large step at the edge will likely indicate a high mileage vehicle. As will excessive wear on the brake pedal rubber.
Another thing I look for is different brands of tyres fitted to the same vehicle.. if evident it smacks of poor care and poor maintenance.
Look for regular and good fitting body panel lines and perfect closing doors.
and walk away if the vehicle doesn't have it's two original keys.
Checking service history and MOTs goes without saying I hope.
What to check when buying second hand