Document everything. Found a useful link that helped you configure something? Copy the link. Finally got your proxy working right? Save the config. Even just make notes of how you set things up.

Refine and build you notes along with your knowledge.

Eventually, consider keeping all your config files in a self-hosted repository like Gitea.

Oh, and when stuff breaks it's probably DNS.

Caddy is a very simple reverse proxy which handles the https redirect by default, other proxies are http by default and you have to manually configure the redirect. Also caddy automatically handles the TLS certificate for HTTPS with http challenge by default (need port 80 open) or with DNS challenge (you need to build caddy with your DNS module and type the API key)

• Can give NixOS a try if you want to make things extra hard and get more satisfaction from finishing. The biggest advantage is most of your OS & services config will be in a file, so there's no need to remember a thousand knobs to tune the experience just the way you want - a text file in a git repo will be all your config.
• I'd recommend Namecheap over porkbun. I found porkbun has less features. I specifically needed to wildcard forward email, which works well on namecheap.
• If you're from Africa, India or some other country where $10 / year is a lot I recommend a 111 class B domain https://gen.xyz/1111b for $1 / year.
• Do you have static IPv4 or globally routable public IPv6 address assigned to your device? I'm ipv6 only selfhoster, and I use inadyn and afraid
• Can use wireguard and then later open ssh once you feel more comfortable.

Are you going to use something like YunoHost or use docker containers and write a few compose files and configure a reverse proxy yourself?