nothing wrong with being self taught, you could follow these basics topics before poking holes in firewall.
VLANS: learn how to separate your LAN into networks with different security requirements. For wireless, try to make a “main” and “IoT” network so that IoT network that can’t talk to your “main” network but “main” can reach IoT devices. For wired, try to have a Management network, and a “Dirty network” etc.
Firewalls and Routing: You will need to be able to route between your VLANS and set firewall rules to allow certain traffic. Best practice is block everything and allow only what you need.
NMAP: learn how to do NMAP scans of your network to discover hosts and their open ports/services. This is a similar approach that “hackers” and script kiddies use on the public internet to find vulnerae and open services. Being able to probe your own network is crutial in understanding how others might approach in penetrating it.
Wireguard VPN: Learn to access your network remotely by setting up a wireguard VPN. Wireguard is preferred because it is “stealthy” and will not respond to unsolicited attempted to probe your network. Start small by using wireguard to access between VLANs so you don’t run the risk of using the internet.
NGINX and Reverse Proxy: If necessary, learn to expose your services or blog or website by only exposing nginx and proxying to your services. Many guides on securing NGINX exist. Try not to expose anything, but sometimes necessary if you want others to reach your website/blog/hosting etc.
That’s a rough outline that you can use to guide yourself and achieve milestones with hands on experience. In your pursuit you’ll run into certificates and domain name hosting and stuff. But all this is on the web so let your curiosity (and paranoia) drive! Have fun!!