What tips or resources would you recommend to someone who knows about Linux and wants to self-host, but has no experience self-hosting?

I have several years of Linux experience and I know how to fix my own problems, and I have experience self-hosting using Docker and Docker Compose, but I really feel that I don't know how to self-host and that I just copy and paste commands without understanding it, I would really like to learn how to self-host by myself but I don't know how I can start or with what resources for newbies I can start with.

I am interested in self-hosting several services, but the one I am currently most interested in is changedetection.io, as there are multiple such services but they all require a membership fee, and I prefer to self-host on my own.