I have found many cannot simply put down #'s on a spreadsheet and start working on PITI, landlord fees, legals fees, etc. Every time you think of a new expenses BUDGET it, and put in expenses. At least half population can not seem to do this. You must get a income/expense projection budget before renting!
Many cannot 'PLAN'. See step 5 above by H. Painter.
Not directly mentioned. If the LL gets to collecting checks gleefully. Newbies may not think or plan for a reserve fee (on expense ledger until filled, plus might contemplate a separate business bank account so can be observed easily). Basically any positive income must fill a reserve rainy day fund ASAP. Once that is achieved you can think of doing something else with positive income.
Yes leniency, that catches my eye. Must be on top of the business situation. Responsive.
An mentioned, NEVER start emotionally connecting, this is a business. Be respectful.
I know one LL that says 'hold on', walks 50 feet away. Acts like he is talking on phone. Then comes back and says my investor says "NO". He has no investors :)
I have in my lease, LL plans to inspect monthly. It can be amazing what you can find from stories I have heard. I also am checking for safety/maintenance too. In NJ we must give a days notice of visit. I suppose will do this by email (documented trail).