How do you test your home network security?

As I'm exploring the idea of hosting my data at home (with offsite backups), I would like to better understand how to test my home network for security vulnerabilities.

I have run basic Nmap scans and confirmed that there are no open ports. I've confirmed that users have access to what they need but nothing else, and that guests using the network for web access don't have any sort of access to data. All data is encrypted so someone stealing the physical hardware shouldn't have access to the contents, either. But that's about as far as I know what to do.

What else could and should I try? How do you pentest your home network?

I feel I'm ok with my understanding of how to set things up so that everything is relatively secure. But I have very little idea how to actually test the setup.

Edit: Added a sentence about encryption.