Find a broker that lets me park license, find my own properties, not be a burden to agents who sometimes hate working with investors, go see listings on my own time, negotiate pricing with an offer of forfeiting my commission, and most of all - not worry about somebody elses convenience / profit.

If you simply want to offer a service for convenience to your residents then using a service is the best route.  

This card allows tenants to pay their rent with cash at the nearest 7/11 store (a convenience store in MI and other states).  

Once they pick a convenient time, present them with a new lease that DOES have a "late clause" or "late fee due date" along with what the late fee is, and have them sign it.

We do major rehabs on most properties we purchase, so it's convenient to re-pipe at that point to enable true sub-metering.  

Conveniently you are reading that website.

I think Jon Holdman has a good idea about how to charge... to add to that, if you still think that's not fair, it might help to adjust perspective by considering the difference in amount can add up to convenience and tuition for this lesson/situation w/your ex-tenant.

I believe Black Diamond has some meetings in Waltham, and RIREIG meets in Warwick, so maybe both groups will be convenient for you.As for your question, tips for someone with investing and business knowledge, I'd say real estate isn't as different from other businesses as it might seem at first.If you're doing buy and hold, each property is a business and the tenants are your customers.

Then I wrote a 0 % convenience check to my account.

That way it is more convenient for everyone.