In the past few years, he has built himself up a thriving custom car audio shop out of a shop rental space in a warehouse park. 

You can create your own custom signs using Vistaprint.

In real estate, it is the tenants (customers) that pay the investors.

If you have worked for yourself for 17 years, then I 'm sure you have provided service to people, you have customers who trust you and value your work , your work ethic, ... etc.

I also have an extensive sphere of influence with all of my longtime customers, acquaintances, etc, so I will be exploring the more traditional home buyer/seller through those connections and organic marketing as well. 

The red markings are where ill bring the backsplash all the way up the wall and im going to put in a custom floating shelf ill make myself 

The seller could remain that broker’s client and you could simply be the broker’s customer.

Good customer service.

I am NOT going to buy custom blinds for this house so my two options are 1. install three standard sized blinds in the window to fill the window space OR 2. install a long heavy duty curtain rod and either put up some neutral (cheap) curtains or allow the renter to put up their own curtains. 

This would, however, eliminate customer retention risk, employee risk, and large amount of debt obligation.