Other investors already taking advantage of the system.

I would start with buying one and focus on ironing out any kinks in your system.

How did some of you great investors make this a business with the right systems and processes to automate and scale properly?

Most of the plumbing was all redone with new combination systems and PEX.

Things such as good school systems, recent new developments in town, a large new employer, or city funded revitalization projects all are good examples of things that can positively affect local market prices.Highlight the renovations you’ve made to the property.

Invocing systems and contracts.  

Once the actual eviction has been granted (through the court system) law enforcement becomes involved to make sure the process goes smoothly.Gail

With the right systems and people in place, you should be spending more than a few hours a month on your rental. 

The problem you have is; if you really want to know how well the heating and cooling system is, and the condition of the roof, plumbing and electrical system then you need to hire a plumber, electrician and roofer because believe it or not general contractors do not specialize in those trades unless they have a license specific for each or any of those trades.The problem I run into when calling contractor for inspections is I get a lot of b.s..

So long story short, in the past 1.5 years, we have renovated 9 of the 24 units, installed new roofs on 3 of the 6 buildings (this was known at purchase), and replaced 8 HVAC systems.