I am self taught but very open minded to all ideas and concept's.

Best bet is to read up on things on Bigger Pockets and attend the local REIA meeting - just search Pittsburgh REIA online and you'll find all the info on the meetings.Start by learning the concepts, etc. so you know the right questions to ask.

The general concept behind investing in real estate as I understand it should generally be to buy a property with that will cash flow if the intent is to rent it out.

First by offering a weekend seminar for a small fee, but at these seminars they only give a vague overview of concepts and engage in high pressure sales tactics to sell their high priced real estate courses. 

Okay, just to clarify, we are getting a few different concepts confused in this thread.Tax Liens and Tax Deeds: This is something different than what I think @Ray Agosto was asking about.

Our big goal is to BRRRR enough properties to replace our household monthly income and do it full time.

I'm assuming you already understand concepts such as Future Value of Money, etc, since you already mention NPV.So let's take a scenario where you buy a piece of property and it gives you $1000 a year in cash flow.

., I haven't done one, I tend to avoid the subsidized deals but the concept is the same as with any property that had an income or expense that is tied to a sunset date where things would change in the future so I think I can still provide a relevant answer.The value today falls somewhere in between what the property would be worth without the tax abatement and with it. 

That's good it reinforces my conceptions. 

If you can not get your head around that concept you face a impossible challenge.