Luckily, the brother left at the agreed on time and I was able to being the renovation.Reno consisted of gutting and replacing the kitchen and bathrooms, replacing the floors, light fixtures, HVAC and roof.

From the paint, to the floors, to the kitchen/bath remodel I'm sure it all looked great. 

General Advice: For those who have successfully transitioned from a W-2 income to full-time real estate investing, what were your key steps?

The biggest thing we started doing after our first 2-3 flips is focusing on the higher-roi aspects such as kitchens and baths, and then doing "just enough" for everything else. 

Keep doing what you are doing and in 10-15 years (your retirement timeline) you'll have a ton of equity built up to turn into whatever cash flowing investment you want at that time (real estate or otherwise). 

Are there separate entrances and does each unit have its own kitchen or is it truly more of a house?

There is some deferred maintenance tenant want me to take care of in the bathroom and kitchen in a 2 bedroom/1 bathroom house. 

Fresh paint throughout, minor repairs, updated outlets/switches, backsplash tile in kitchen/bathroom.

Find out if there is a wall with convenient access to plumbing drains. and if that area could work as a kitchen.

Why pay $2,000 more and then run the risk of damaging the kitchen table or spilling wine on your white chair and having to pay for a replacement?