Start with BiggerPockets Ultimate Beginners Guide (free).

The fact they are complaining online might be an indication the property manager dealt with them properly so be sure to ask the manager for their side of the story.I hope this basic guide helps.

@Stephan Kraus I am currently almost done with their second version of ultimate beginner's guide to real estate investing.

(Spoiler alert) -  I didn't end up going to college and I gained a lot of valuable insight from the responses I got. 

Check out the free guides under the education tab above.

Valuable free information on this topic. 

This keeps the group of friends form using valuable networking time to maintain the personal friendships.  

I'm extremely new to this world, but very eager to learn, and be successful. I'm dedicated to learn the ins-outs of wholesaling, that's what direction I want to start in, then go on to rehab/flip, then to rentals. If ...

We hooked up with a local reputable realtor who has guided us through the whole process as newbies.

@Gene Bonham Probably not interested in the vacant lots unless it was a particularly valuable location, but as far as buying a lot to build a house, I am not interested in new construction.