@Corazon B. There is a lot to make sure is good to go and even if you line up all those ducks in a row there is always the possibility of one. Have you considered a property manager, sounds like having one at least in the beginning could help build your confidence. With that said where are you renting the unit? The requirements will vary depending on the city and state.
With that said, if you're going to self manage a solid lease will offer you some protections and also making sure you do thorough tenant screening (to include reference and background check), holding the security deposit and unit funds seperately (depending on state/local laws but never a bad idea), and once the tenant gets ready to move in a solid pre occupation checklist with photos to document condition of the property. Having solid insurance and requiring the tenant to have documented renters insurance means their insurance gets the hit if they decide to cook bacon naked and start a fire (sadly I have a friend whose tenant did just this).
There can always be more, but this would be a general starting point. Hope this helps!