1. Check Zoning.
2. Soil test and engineer the foundation.
3. Check with building department for any other restrictions...type of house, height, setbacks, area zoning, etc.
4. Crime Rate
5. Availability of services.....water, sewer, electric, cable, internet?
6. What was there before? You likely don't want an enviornmental cleanup. Was it a farmer with storage tanks, gas station, farm house with septic tanks, lead smelter, or what?
7. Sat photo of area so you can see what is behind the trees.
8. Check wetlands, architectural, heritage, or other historical/environmental restrictions.
Those are just a few....there could be more depending on the size, scope, location of project.