Create the reporting mechanisms so they have a good UX, such as putting simple icons near the data that would need to be reported, like a post. Then make sure you have staff trained well to moderate the reported data.
Reporting things. Being polite…basically be more like the child your nursery school teacher taught you to be and less like the jerk that so many keyboard warriors become.
Make it easy to block a user and make it such that as soon as you block that user all the user content will not be shown to the user that blocked him/her. Count the number of times a user is blocked and decided if and if yes by which count you look into the user behavior and think about a global block