This has a lot to do with I'm new into real estate from the medical field and iv also never bought a house even for personal use.

@Ethan Reiniger, there is a lot to consider here.  

There is only so much you can do to a bare lot to increase its value,  prior to the house site being determined. 

Yes, but you need to narrow it down a lot to have a coherent answer.You will have to look at (I'd recommend in this order) the city codes (if it's inside a city, many cities above 50-100k population aren't friendly to development of these), the county codes (most counties are friendly to these, but you will probably have significant issues in major counties like Bexar, Travis, Dallas, Denton, Tarrant, Harris, etc), then you will have to comply with the state-level (TCEQ and others) on the water supply and waste water treatment systems.To put it in perspective again, in say Dallas or Austin, you will likely have prohibitions or very significant hurdles on developing RV or tiny home properties even on unincorporated, "unrestricted," AG-zoned properties at both the city/municipal level and county level.

You've given me a lot to think about.  

I want to make money but don't have a lot to start.

.“$500 is a lot to spend if I don’t have to especially if I’m not even sure if I’m going to be able to get a loan.

It would be better to replace the plywood and the floor joints but thats a lot to.

Howdy I'm buying a vacant lot to accommodate my business (contractor).

Well, there is a lot to consider besides just the normal cash flow and ROI.