Couple of things.
When you screen your tenants, don't just call their current landlord, call the one before that too. The current landlord may say anything to get rid of a bad tenant.
This is probably not totally above board, but after I hear what a reference has to say, I always ask what they can tell me "off the record." Sometimes the replies are night and day compared with what they originally said.
Form a property management company, and represent yourself to the as an employee of said company. That is factual. When things go right, you can take credit as the property manager. When things go wrong, it's the owner's fault. There's a little more nuance to this than I'm stating here, but I think you get the idea.
Never ever, ever, ever, ever let a tenant pay less than the stated rent on the lease, including if they absorb some kind of repair or do some work for you. My ironclad rule is that they pay the full rent, and then we reimburse the amount that was previously agreed to. Many tenants, often with good intent, are willing to do some work and knock it off the rent. That starts to open the door you probably don't want to go down, because eventually there will be a month where you get a light rent check and a note that they made some repairs for you.
Qualify buyers before wasting your time on showings. Have them complete the application. If possible, collect a small application fee from them, even if it's 5 or 10 dollars. Stack up all the showings at once. Get everybody there on Saturday from 1:00 to 2:00, or whatever.
This is more market specific. I have had my best luck with tenants placing small ads, flyers, or business cards in the locations where my tenants might frequently visit, such as local stores, laundromats, etc. I have found this far more fruitful and cost-effective than any other method, although I am happy to take suggestions that you or other people have on methods for finding good tenants. This one has been working for me in the meantime though.
In the long run, your time is better spent looking for more deals and closing them. To do that, you either need to get the property management down to a science that takes almost no time, which is totally possible, or eventually you will need to find someone to do it for you.
Increase your rent by a small amount frequently, like at least annually if not every 6 months. Tenants adjust to that better than a large increase further down the line even though technically it's in their best interest due to inflation.
keep it all business. They are not your friends. The relationships may be pleasant, cordial and you may even make some small talk, but never expect, even for a moment, that Goodwill that you show in one time frame will be recognized in another. The less they know about your personal life and all that stuff, the better. I have great relationships with my tenants, but they are business relationships.
Have them pay the rent electronically. It doesn't matter that you're 5 minutes from the house. You'll end up making 10 trips cuz someone's not home yet or whatever. It also sets up an expectation that they only have to pay the rent if you go get it. There are a variety of tools for this, and they are a beautiful thing because they timestamp everything.
Although I learned that this is getting banned in some places, I have always signed my lease is with an addendum that there is a $50 discount per month for on-time payment. When payment is not made on time, I can simply send another invoice for the $50 and say that this month did not qualify for the discount. This is, in effect, restating the late fee in different terms.
Similarly, and I believe this is still legal, you can have an addendum where they receive some sort of credit for taking care of things like lawn, leaves, gutters, snow. This doubles is making sure the property is taken care of, and gives you leverage if they are not doing a very good job. Just make sure the credit for one month is enough to cover roughly one month of those expenses, otherwise you might find yourself in a losing situation.
good luck! Managing tenants has been tough from time to time but definitely doable, especially with systems.