Official docs (Alpine wiki) are the best resource I found so far.

You can start by watching a tutorial install. The scripts alpine has make initial install fairly easy, steps from there are just like any other distro, same concept, diferrent utilities. Either way you find yourself on Alpine and Arch wiki or Reddit searching for ways to do something. Also, neverunderestimate Manpages and --help, if there are no docs online, your answer is likely there.

Note that some things are not fully covered on Alpine wiki and they do refer to Arch wiki articles.