Carfax and/or service records from previous owner(s) is a must. If buying from a Ford/Lincoln dealer, see if they will pull the OASIS records for you - records of servicing at Ford/Lincoln dealerships.
Definitely avoid cars with major accident damage or flooding unless this is a project/hobby car. Cars with rear end collisisions even if relatively minor can end up with damaged AWD systems.
Look into what warranty comes with the car. May still be able to get a basic powertrain from Ford Protect after an inspection, as they warranty out to 149,000 miles.
Figure on new tires + alignment. Possibly shocks n struts too.