Check your local real estate association meetings as a resource.I also like the idea of house hacking mentioned by @Travis Timmons and @Nicholas L.  

Apply for a dimensional variance on the vacant lot to allow a smaller lot and/or setback so it can be built upon.Your best first steps are to sketch a plan, possibly with an engineer's help, then contact the zoning department to discuss your idea with them to get informal feedback on your liklihood of success before you spend a lot of money.

What you need to learn in your 20s is how professional business works, how to manage people and projects, how to run an organization and how to sell ideas and concepts.

Both companies have recently closed on transactions with people new to the industry who have no idea how much their current investors are hurting. 

On another note, I don't like the idea of paying all-cash. 

Move into the house for a while (there are spare rooms) and get a better idea of what is going on.

And yes they pay 60% of your Mortgage.Open to share ideas any time we have a free network to meet like-minded investors in Miami.Luis Maqueira 

I know of a couple of good PM's if you need them and can give you a general idea of the best areas to invest in. 

@Mary Peale - Hi Mary, I have a couple ideas that come to mind.

Also you seem to not have a team in place, BAD idea.