What are some lessons y'all have learned from your rentals that you think nobody should make? Best things to put in your leases?

I have one tenant who's been here a long time, before I started not officially including internet. Now I say "I sometimes share mine with people as a courtesy, but it's not included-- if the person makes my internet ...

I've been interested in real estate for over a year. In that time I have read God knows how many books. I have "partnered" with  a friend who has hard money connections.  I've been going through the pre-foreclosures f...