He has had a free ride for too many years with his previous landlord supplementing his rent.

Why would you choose to supplement your tenants rent out of your own pocket.

REI) to supplement your 401k. 

I consider myself a successful investor because I am able to live off my rentals with no supplemental income if I choose, which is the goal of many in this forum.

Long story short, I began researching the deregulation of energy, and found that I could become a broker for lack of a better term for energy and supplemental services.  

You are not asking to raise his rent you are telling him your are raising it.You should also not be supplementing his rent.

When the proceeding supplemental for interrogatories  was served, it was I who sent the forms to the Sheriff and paid him for serving these forms. 

I started researching real estate investing when my mother's rent started going up and I figured the only way to not end up supplementing her at some point was to purchase something in order to create "rent control" so to speak.

I’d like to supplement my income with passive cash flow and continue to re-invest to give myself the opportunity to retire early.I currently have $20k saved up as cash, and $10k in an emergency fund that I could dip slightly into if required.

That's what investors do.But is investing what you want to absorb you or are you a casual investor who loves his career and is investing to supplement or prepare for the next phase of life when it happens?