Advertising (photos and listings.) turn over costs, snow removal, and those kind of things.

A mortgage broker is one who is in the business of dealing in mortgages or notes, it is their primary source of income, they advertise and seek out note purchases and sales, there is a thin line between being a broker or in the mortgage business and being a personal investor. 

It's only 110V but would be nice on the property advertisement for potential tenants.

They will not offer that (instead relying on your advertised rate), but they will be willing to pay what you're asking without fuss as long as it is below that high threshold.

I've seen people on FB advertise cold calling services which seems interesting.

Do you advertise and show properties BEFORE a tenant moves out?

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

You just advertise that free pool/landscaping is included. 

We live in an electronic world so people don't favor doing that anymore.

These will allow you to advertise in an area where viewers are actually looking for a new home or apartment.2) boost your listing with a small daily budget.