A year ago, Mickey Petersen published Mastering Emacs, an excellent book for beginning and intermediate Emacs users. Oddly, although I've seen many tweets praising it, I haven't seen any reviews. Happily, the prolific Artur Malabarba has remedied that.
If you don't already have your own copy of Mastering Emacs, take a minute to read Malabarba's review. I'm sure it will convince you that you're missing out. Even if you're relatively familiar with Emacs, you're almost certain to learn a few things. I know I have.