The things that you need to do before you put any money into a new property are going to depend on what exactly you plan to do with that property. If you are buying it just to plant a garden, you need to make sure you have access, and a healthy water supply with which to tend it.
If you plan to build anything on the property, you need to make sure you have enough land to meet the building code requirements. You also need to make sure that the type of building you plan on is the type of building you are allowed to have there. For instance, you may be in a residential area, but plan to build a business. You have to see if that will be allowed. You might also have the desire to build a home in a commercial area and need to have it approved before you proceed.
Most importantly, you need to be aware of what you are legally allowed to do in your area. However, you can almost guarantee that whatever you do on the land, you are going to have to have an adequate water supply. You can test drinking water before you build. When you test drinking water, you can learn about the minerals and other elements that are in your water so that you know if you can use it, or if you need to do something to it in order to make it usable. In some cases you may not be able to use the water at all.