Are you talking about land to build one home? to subdivide? for future investment appreciation, to build a farm? a ranch? to simply be a land-baron in the less-populated geographies?
Very broad question: You need to check Zoning restrictions if for a home---You need to check Usage what can ultimately be done w/the land if future investment---can it be a residential neighborhood, etc. Water lines, sewer lines? Otherwise well & septic.....if septic, you'll need engineering and perc tests to insure the ground will "hold" the waste.......Yes, you can always build systems, no matter what type of perc but you may be in for a huge expense that you did not anticipate. If for just one home, most important is to look at the surrounding neighborhoods and usage for "like-priced" homes and no industry, that will insure a good investment. Some areas have "wetlands" designations now, the grounds are too wet for usage and cannot be built on. Check for massive rocky areas because you will need to blast if you plan to build....This may just be a start of ideas, based on your broad question?