I am in the process of suing him and just finding out now that he's done this not once, not twice...But 4 times AT LEAST.

My process involves two steps.

It's the simplest way and walks them through the entire STR process.

I would notify her in person and in writing (big note on her door) including quoting the clause in the lease where she is responsible, and tell her you will be inspecting to insure the heat remains on, high enough to protect your unit, or she will be breaking the terms of her lease and also liable for any damage done in the downstairs unit as well.

This ensures that any payout for damage or liability can be processed more smoothly, and it can help protect your interests if something happens on the property. 

For your first rental property, starting in an area you're familiar with can make the learning process easier, as you’ll better understand the market and can handle issues directly.

Rents will rise much at a much faster rate, so the challenge of finding cash flow (enabling more investors to become "capable") will gradually recede as SFR cap rates gradually expand - it will be a process, not an event - over the next few years.

I'm in the same process and have the same question.

Just document the current condition before the cleanup process and follow any other local law or procedure that is in your municipality. 

The more you know ahead of time, the easier the process will be.