I contacted that agency this week online & got a response they are not writing commercial properties now. 

That's what I've heard from others and read online as well.

I’m always looking to implement best management practices so what can I, as a landlord, do to protect myself when accepting online payments?

As we can see the average retail investor is still quite negative.

Though I appreciate the idea of finding online resources and studying them, I find that a curated, tried and true formula (if it works) is much more worth my time than spending time trying to find which resource works best and then spitballing the ideas until something sticks. 

@Yosef Ajami, we use Quickbooks Online for all of our Clients (including syndicators).

My background really comes more from construction and development in residential and retail construction.

So here is what I do:1 - Get buyer criteria for what they are looking for (exact criteria)2 - Go source that criteria using data provider3 - Scrub the list and plan a marketing campaign around it (i.e) > Direct Mail > Cold Call > SMS > Online Ads > Social Media, etc4 - Once I get inbound leads coming in.

On top of that, when you go to sell you learn the market has been stagnant and has not appreciated with limited owner occupants & investors are not willing to pay retail given the amount of distressed inventory that exists in the market. 

Even though I myself have a S8 rental, what you hear online is completely false.