We have spoken before about being a mensch, and about getting started with your project. In the latter we covered how you need to ensure that your project has a licence along with (ideally) a code of conduct or contributor covenant of some kind. Having these documents is, however, only the first step along the way of ensuring your users and contributors are protected.
Sadly if you're not on top of things then these documents are not worth the bits and bytes they're made up of. You must enforce such things in order for them to be useful. Fortunately if you pick a licence such as the GNU GPL then the Free Software Foundation carries some articles about enforcing the GPL. In addition, the Software Freedom Conservancy may be interested in helping you.
In addition, social contracts also need to be backed up with positive action in order to ensure that current and potential contributors can feel safe engaging with your project.
Your homework for today is to check over your projects again and ensure that they're all carrying appropriate and enforceable licences, and where appropriate social contracts, codes of conduct, or contributor covenants. Then once you've done that, take some time to check any community you might have around your projects for people failing to honour the codes of behaviour the project expects and deal with them politely but firmly. Finally take a bit of time to look around and see if you can see anyone violating your copyright by using your project in a way not covered by your licence. (For example, incorporating GPL code into something without offering the source).