Flame war between bash/fish/zsh/powershell is almost meaningless to beginners, because the basic skills are common to all shells. (That said, you will love zsh once you use it)

I learned to use shell, about 7 years ago, by reading O'Reilly "Classic Shell Scripting". It is well written, and teach you something that you can hardly learn from google. But don't try to remember everything, especially those advanced string manipulation syntax, because one would usually use a scripting language such as ruby for advanced job.