Here's a list of things to track:- Formal lease application- Formal signed and executed lease specific to your state- Payment history (I recommend using online rent collection like Apartments.com, RentRedi, etc)- Maintenance requests and receipts- Accounting for all rental-related expenses (repairs, utilities, etc) The more you treat it like a business, the more helpful you are to your CPA come tax time. 

Now I found one that specializes in real estate investors that was recommended by an online mentor.

I saw this online the other day.

Start by networking through local meetups, REIA groups, and online communities like BiggerPockets to connect with experienced investors.

Later that night, we reflected on what went wrong.

I teach CE/CPE for several tax organizations at conferences and online so I talk to A LOT of tax professionals.

If you were going to focus your time on learning something, I'd say getting familiar with a bookkeeping platform (like Quickbooks Online) would be the best bang for your buck.

I too, have looked seriously into the many, many, online Real Estate Guru’s that are offering one on one training.

 try one of those online sources like prosper etc. 

Also just look online and steal some ideas...I used to Google Luxury Kitchens and then figure out how to do the same for less $$.You'll be fine with your experience.