PostgreSQL is my favorite relational open-source database. Here are some tips & tricks I have found useful:
Make sure to kill inactive database connections. I had an issue a while back where my server was not able to connect to my database. It turns out I was hitting the maximum number of connections. This post helped me identify the issue. I ended up setting the timeout to 60 seconds and this cleared up a lot of the unused connections. Many of them were old connections from my local development database management tool, DBeaver (which is awesome by the way).