Launch a high converting website (that's what we do) and run some low cost ads for seller phrases like the above and do some basic SEO (much easier to rank for land phrases than house phrases). 

What marketing strategies are the most cost effective?

The best strategy is to not quit your day job until you've built a portfolio big enough meet your income requirements.You have three potential paths.  1) Build an active investing business, something that takes time.

The strategy is built on your own personal cash flow commitment.

Getting into real live action (not meta) will connect you to your next real partners, and new stream of income strategies.

I understand that a lot of units in ATL are now accepting section 8, so newer, nicer properties are taking the tenants.Possible strategies:-Just lower the rents to the lowest price I can find for a 4BR in Atlanta -- probably around $1200 or $1300, and get a market tenant in there.

What are the best strategies to sell my single-family rental property at Sycamore Ave, Grandview, MO, that still has an active mortgage/loan to achieve the highest top dollar?

I completely understand the hesitation about paying a recurring fee when many of the biggest value-adds—pricing strategy, design, and preventative maintenance—are front-loaded efforts.

But it is a job and mental drain/distraction- there's always something.With all of that said I'm trying to formulate an exit strategy. 

Now I'm considering selling it while it's still under mortgage and hoping to get top dollar for it.What strategies would you recommend to attract serious buyers and maximize my selling price in this market?