I know most people aren't doing this, but... Y'know, if I came here from twitter and the first thing I saw was fedi users telling me "welcome to fedi now do this and do that" I'd be like "da fuq". It'd turn me away tbh. When people join new communities, what they usually like to see is "hey welcome :3" and maybe throw them a small conversation and, if you like them, a follow to get them going. They'll learn the specifics eventually; most people want to start with a warm welcome and don't want some sort of social media mentoring.