CIRCLE WITH A DOT

How does one audit a home network reasonably? Thinking of setting up some self hosted stuff that may involve internet ingress.
I can DMZ a machine, but it's an i-dont-know-what-i-dont-know situation. Are firewall rules enough? How much should I actually be worrying about someone getting access to my local network segments?
#infosec #cybersecurity #diy #selfhosting