tips for buying land

[Fred Conway]

im looking for tips/do and donts for buying land. I understand the buying foreclosed land or somebody didnt pay they're taxes on it but looking for what actually will make land valuable as well as what to stay away from. Is it better to buy land in a suburb in a neighborhood or buy something in the middle of the city and hope it appreciates. 

Also, Im seeing things like buying 10 acres but only 7 acres are liveable and theres no disclosures, what exactly makes land unliveable besides toxic waste or something along those lines?