I hope other experienced investors can point us to single sources, but suspect the tools and knowledge is gained from many angles (books, podcasts, seminars, mentors, etc.) and experiences (successes and failures). 

Seemed knowledgeable and like he knew what he's doing, owns his own properties and manages others alongside them for additional income.Have not had him long enough to gauge whether this will be a success of a failure, but there are some red-flags that I didn't notice when signing the contract.

Oklahoma has a school system that is on the brink of complete failure and with it's current political realm and laws protecting change unless 75% of house members pass a bill, they are in deep deep trouble.

I ended up getting most of the rent on the 16th, at which point my requests to find a new place broke down and I knew we would likely have to evict based on failure to pay rent and late fees.

You will likely face more failure than success when you are starting out.

We do not currently have the funds to absorb a failure of the heating system, but there's enough income to budget 10k annually for capex and still hit a 10% cap rate, so it's something we could remedy within the first year or two.I reached out to a business contact and asked if he would secure contingency funds in exchange for a percent of AFFO (basically, we'd pay him a portion of the income in exchange for the right to use him as a private lender in the event that one of the systems failed before we replaced it).

School failure has nothing to do with lack of funding.  

I was the one making the decisions.It took that failure as an investor to learn to be patient. 

When researching my own fridge a few years ago, I was dismayed to see that initial failure rate on lots of new fridge's seems to run pretty high these days.

@Erin Auman Sometimes failure is the only way to learn.