It depends on what you want, but here is where i started:
I watched a lot of youtube videos about opensource software. Then i got a nice second hand server that was quiet and didnt use too much power. I installed ProxMox on it instead of VMware (opensource) and then i slowly started to build VM’s for whatever i wanted to selfhost.
A very important aspect that a lot of users ignore is security. You need to keep everything up to date. Follow sites with regards to your software (you can aelfhost freshrss. So thats a nice start) and keep “up” with cybersecurity.
These days i have a small server with Alpine installed on it. Since most my selfhosted things now come in docker. If you go that way, learn yourself everything anout docker and docker compose. Compose is a really powerful tool once you work with docker!
I’m not at home now, but i will try to remember to post you some links to rss feeds i follow :-)