When you are doing Location you are doing it for the specific application. The requirements for the site survey should really come out of that application. Ie: if you are working with AeroScout you have to have their requirements for the network you build drive the design.
Some familiarity with the location services will be also important. The way you position access points (no streight lines), creating wireless perimeter first (as oppose to installing APs inside the zone reaching out to the outside), minimum SNR requirements for the 1st, 2nd and third APs (potentially more), AP density etc etc. Its a large topic and your location vendor should help you identify the requirements that you, as wireless designer, will have to meet.
Does that answer your question or you need more specifics?