I think the easiest way to start would be to call a couple property managers and so them.

IMHO fixing the houes is the easiest step.Please jump into your education;  how to find deals,  Most importantly how to evaluate the deal, how to negotiate and close. 

For example, like most presidents since JFK, Biden is using the Resolute desk, a gift from Queen Victoria to President Rutherford Hayes in 1880.

But are there some off-market opportunities can be found these days and what are the easiest ways to find them? 

To encourage them to pay online on a scheduled recurring basis, I was thinking of offering them a one-time gift certificate.

I use them and give them away to my house hacker clients as closing gifts. 

Google search is the easiest, other option is to call up any lender and they can tell you the requirements.

@Robert Ruschak as others have mentioned, scaling up quickly is not necessarily the best approach for a beginner (and in fact, it can come with some serious risks).RE is just like anything else in the sense that you usually want to start off with the simplest, lowest-risk, easiest to learn strategy (like house hacking). 

I like the tenant bonus idea and something similar is offering them a gift card to the local coffee shop, restaurant, etc., as an incentive to get them out for some time.

@Todd Mathisthere are other options like 203k loans etc. i will say hard money will be your best and easiest bet, most likely. i have used it many times and it was instrumental for me.