Check references of the CPAs you engage with, our Utah based firm was well advertised, but i started learning through my mastermind group of several customers that had major, expensive errors on their returns.  

What are the Uber/Lyft rules around advertising "we buy houses" to your passengers? 

I think that this may draw attention and traffic to my website or advertisements during vacancies.

Start calling landlords that are advertising.  

If you are reported the burden of proof is on you to PROVE you are not brokering without a license.See 475.43Sure you can assign a contract but when you start advertising the house you are NOT selling the contract you are indeed selling a house.

We recently bought a condo in Branson, MO, and it's going pretty good, but I advertise it on VRBO, and I've had some customers turned off by the service fee that VRBO charges.  

Aside from what @Steve Babiak added, one item I would add is that if you don’t pay to advertise your vacant units, I would immediately start advertising for a new tenant around step 1 or 2.

I've been interested in real estate for quite some time now and I've even invested in Direct mail campaigns but I've noticed I'm dragging more at work now because I feel as I need to quit my job because it's 12 hours a day and I'm not able to spend time on Real Estate like I want.If I leave my job less money for campaigns but if I don't leave my job I feel like I'll always miss calls and be unable to meet with sellers.

Try advertising it on here, craigslist, and local FB and REIA groups.  

They advertised sales of $14,9/$19.9 and up.