Before you upgrade to macOS Catalina, which just came out, check to see if your apps will work. Old 32-bit apps don’t work in Catalina. So run Go64 to see what apps are still 32-bit.
It’s also a good idea to have backups. In addition to Time Machine backups, I like to have SuperDuper backups. That means I’m going to wait until SuperDuper software working in Catalina.