Adjacent to toxic waste dump site?
Heavily insure it, attach a lightening rod and pray?
Your best allies will be a good architect and soils engineer. Preliminary homework prior to purchasing the land should be completed: The Architect should verify property use, allowable builds, associations governing area, and basic requirements for a home. The Soils Engineer should verify that the land is stable (soil condition, earthquake faults, flooding..), and suitable to build on. He may be able to do so from experience in the area, or a soils test and report may have to be generated.