If you're in Canada & want to homestead:
Check the provincial & federal government sites for:
Garden zone-determined primarily by winter temperatures,
Heat hours-determined primarily by summer temperatures,
Abandoned mines or oil fields & potential future mines or oil fields.
Radon sites,
Natural contamination (for example one area north of where I am has water naturally contaminated with arsenic)
Earthquake zone? Hurricanes? Flood zone? Other disasters that have been known to occur in the area.
Fresh water generally available?
Soil type. If the provincial agricultural ministry states that a certain geographical area is suitable only for cattle, believe them. Someone, probably many someones, will have tried and failed to raise crops there.
This is what I would call a basic due diligence list.
Site specific- don't purchase till you're certain you'll have water. A local farm just went to crap after 13 years of hard labour. Their water supply dried up. It happens.
Check the soil of the specific property. The property may be in a great area generally, but that specific piece of land might be naught but rocks. Bring a shovel.
If you're going to be rural, you'll be responsible for your own septic system. How easy/difficult will it be to install or maintain?
Try and see the property when it doesn't look good. When problems, like too much or not enough water are more apparent.
Many rural properties are sold by the homeowner & never listed on MLS. So check Craigslist & Kijiji as well. Some don't even list there. Pay attention when driving through the area.
When closing in on an area, check municipal & provincial planning for stuff like future roads. Check out the land title office. You'll have an idea of assessments, mortgages on the property (they're unlikely to sell for less than an outstanding mortgage. Which might make the property overpriced.)
Rural properties can be on the market for years. Or disappear overnight. Prices can be all over the map. $60,000 for half an acre. Or 100 acres.
One last point: realtors are working for the seller. Always. They do not have your best interest as their focus. They will show you around, that's how they make their commissions. Also be aware that in a rural area the realtors will be fewer in number-and show only their own listings!
Sorry this is soooo long. Hope it's helpful. And best of luck.