From my experience, taking it step-by-step has helped me avoid mistakes and build a solid foundation for the long term.

My first thing is to start built relationships with realtors and property managers.

They sell an older inventory unit, get all there appreciation and equity liquid, and use it to secure 2 new built units. 

I was previously with Foundation Property Management, and they consistently mis-managed (horrible tenant selection, extreme rehab costs,...).

this works well if the tenant is a national user or multi unit operator who has built these buildings many times. 

Again, if your $250k is true, and includes all the electrical upgrades, new plumbing runs, potentially new foundation pour (since I assume the existing garage slab is not capable of supporting a new two story house), I am guessing since I don't know the market, but assume you will have a lot of equity by completing the project.

Quote from @Kyler Tarr: I am on contract to purchase an investment property in Ohio and the inspection showed the house has knob and tube wiring even though it was built in 1959.

The original goal, rightly or wrongly, was to maximize rentable units, so we rebuilt the main house from the foundation up into a 3 bed 2 Bath 1,600 sq foot main house, and added a 600 sq ft 1 Bed 1 Bath JADU, along with a 1,200 sq ft 3 Bed 3 Bath ADU.

I’ve built a ton of solid connections with reliable contractors.

Purchase price: $55,000 Cash invested: $440,000 Currently under construction and pre-leased for $6,195/month, this 7-bedroom, 5-bathroom student rental in Clemson, SC, was built using investor cash and designed for high-end student living.