First thing is to find a lot in an area you would like to live in. Next step is to go down to your local building department and local assessor's office and get the assessor parcel number for that lot. Then ask your building department to look that lot up for you and find the zoning for that lot. That will tell you if you are looking at a single family home lot of a multi-family zoned lot. If is it in a residential area chances are it will not be zoned for commercial use however if the lot is close to the down town area it may be zoned commercial but whatever the case you will be able to verify that once you get the assessor's parcel number. Then you should ask what are the property set backs on that particular lot that means how much land you must leave open at the front, back and sides and how much you of the lot you can cover with building and how much has to be left free with nothing on it like maybe 50% or some number like that. You should ask if there are any easements on the lot meaning right of ways established for whatever reason but frequently those right of ways are created to give the adjoining lot access to a publish road or a utility company access for their service equipment. You then need to know about the kind of soil you have at that lot and if there are any drainage issues.
You will also want to know if any improvement on that lot need to have a city council approval or if your neighbors will have any right to say anything about the kind of improvements you can make legally on that lot like how high the building can be etc.
You should also ask if there are any municipal service at the location or near the property line to your lot like city sewer, water, gas and electricity and if now what you will have to do to get those service there. Ask if you will have to have a septic system and what are the requirements for a septic system if you will need one. You want to have all this information long before you really consider buying the lot. Of course you should also check with contractors in the area to get an idea as to what they would charge you to build a house on the lot including a garage, discuss all matters with your local building and planning departments. They usually can do a good job of cluing you in on what all you will need.