Emacs Lisp has a reputation for being difficult to learn but as I’ve said many times, the main difficulty—especially for someone already familiar with Lispy languages—is learning the text-editing specific functions. Most of the rest is just standard Lisp. As Jean-Philippe Paradis so neatly put it, for a Lisper, learning Elisp is more like learning a big API than a whole new language.
Xah Lee recently updated his page on Elisp functions that every Elisp programmer must know. If you’re just starting out with Elisp or are a bit rusty and want to get back up to speed, this is an excellent resource. Lee doesn’t cover every function, of course, but the vast majority of “scratch my itch” coding you’ll do can be implemented with these functions (and the standard Lisp functions).
One nice thing that Lee has added is embedded documentation of the functions. If you hover over a function name, the standard Emacs documentation for it pops up. That makes it easy to get more information on the functions as you read Lee’s article.