I tell my renters right upfront I have a ZERO TOLERANCE policy for late rent.

It won't work after this as I have a low tolerance for people like this and made it clear the $50 was a one time "courtesy".

At the most you might want to send out to all your tenants a reminder of no drug tolerance on the premises.

Read through the lease with them line by line and make it clear you are a no nonsense landlord that will not tolerate late payment or breaking of rules.

All depends on your risk tolerance

I only value good tenants on the first of the month and make it clear to every new tenant that I do not tolerate late payments.If I buy a property with below market rents and tenants move out I get to bring in my own tenants.

@Gerald Demers You're lucky that the moderators are treating you kindly (while you are new to BP, at least) as you have shared outside resources and websites, which seems to upset them.Also, you suggest that people actually spend money, which appears to be another thing that is not PC to the newbie-biased moderators.I also agree with you and Flyboy Jay that part of the nuance of investing is knowing what research  to do when, and to know your own tolerance for risk.

However, we aren't aware of this individual's risk tolerance or financial situation.  

Once the protocol is established you end up with a properly run rental property that does not have vacancies but if necessary tenants are tossed and quickly replaced.Tough management is far better than landlords having to supliment tenants rents and tolerate bad behaviour out of fear of experiencing a vacancy. 

I would be evicting a racist tenant while demonstrating to the other tenants what behavior is acceptable and that our properties will not tolerate tenants that disturb and/or harass other tenants.