Some people handle confrontation better than others. When you dive into the rental business, though, you should be certain that confrontation will find you if you want it or not. There will always be those tenants that no matter how well you plan, no matter how well you screen, and no matter how well you manage will always
drive you just a little mad. The ones that progressively get later and later with their rent every month are the worst because when they don't pay you, you often can't pay the mortgage or the maintenance bills or any of the other bills piling up. Often it seems that the more delinquent tenants don't understand or forget that you are a business person, not a charity.
It's always good to have a policy in place from day one on how to handle late rent. Rent is due on the first. A grace period is provided for three days, but if by the fourth of that month it's not paid, late fees start. If by the fifteenth the tenant still hasn't paid, the eviction process begins. That's just an example, but you get the picture. Some landlords prefer to avoid late fees all together and skip straight the threat of eviction.
Don't be afraid to contact your tenant if they do not pay. Call them, text them, or write them an email. Try to get a hold of them by any means that you have. You'll want to remain respectful in everything that you do and document everything (date, time, and everything said) in case you need it later on. Don't let them get you worked up, even if they are. By standing firm to your policies that you provided from the very beginning you're showing that they cannot get away with simply not paying.
BiggerPockets has a great article on what they call the Blitzkrieg Rent Collection Plan
. It helps set up steps to take to encourage tenants to pay on time and build respect between you both as a landlord and tenant.