First off, learn how to screen potential tenants. This one took me a while but never underestimate the BS people will sell you to move into your place. Learn how to navigate your local municipalities's court records. If you find an eviction or an unlawful detainer, do not rent to them. Don't focus too much on credit ratings. Sometimes, tenants with lackluster credit can work out great assuming they have the income ratio covered. The low credit will often keep them there longer since it's a barrier for them to buy a home.
Second, treat these tenants with the utmost respect. If something breaks, fix it immediately. A mutual respect for your tenants will encourage more timely payments, better care of your property, and most importantly, less turnover.
Speaking of turnover, this will most likely be your #1 expense. With that said, do not feel the need to automatically raise rent at the end of every lease if the market doesn't dictate it. Some no-nonsense investors on here have a rule that automatically adds 2-3% at the end of every lease. IMO, this just forces people our prematurely and any potential gains are washed out with an empty unit for a month or two.
And lastly, if you are managing yourself, learn how to fix things. There are simply YouTube videos on anything imaginable from replacing disposals, fixing dryers, etc. Not only does this save you money, but it will help you build a more solid business relationship with your tenants.
Ken