Reddit mentions of Writing GNU Emacs Extensions

I learned the basics of Lisp from this
book, which you can get online for free. Although it's about Common Lisp you
can translate most of it easily to Elisp, just (require 'cl-lib) and you will
be fine. For another quicker but great introduction to Lisp I recommend
reading the first three chapters of
PAIP

The old Writing Gnu Emacs Extensions
still serves as a good introduction to learn Emacs APIs. I also learned a lot
more about Elisp reading nullprogram.

Reading code of small packages which solve something you are interested in is
another great way to further improve your Elisp skills.

As far as configuration and general setup goes, I think this Steve Yegge article is probably the best: https://sites.google.com/site/steveyegge2/my-dot-emacs-file

As far as a good intro to emacs programming, I recommend the book 'Writing GNU Emacs Extensions' by Bob Glickstein http://www.amazon.com/Writing-GNU-Emacs-Extensions-Glickstein/dp/1565922611

It is an excellent guide to writing elisp code. It starts very gradually with simple "how to make emacs more comfortable" chapters, to writing a minor mode to writing major modes. Don't let the age of the book fool you, it is still 95% applicable to modern emacs.

> It is a real Lisp and a good starting point

While not directly related, there are a lot of classic Common Lisp and Scheme books that while not explicitly the same as Emacs Lisp, wrinkle the readers brain in a way that is useful for coding in emacs lisp and becoming a better programmer in general IMO.

All of the texts I have read that are listed on A Scheme Bookshelf and A Lisp Bookshelf have been great reads; also they are excellent texts for reference on how to make great technical literature on par with Donald Knuth's books with respect to quality of presentation.

Writing GNU Emacs Extensions is still mostly relevant, despite its age, which IMO is a testament to how timeless Emacs is.

An Introduction to Emacs Lisp is great, and also included with every Emacs installation.

I'd recommend watching Writing Games in Emacs for a simple tic-tac-toe mode and then reading Writing GNU Emacs Extensions which culminates in a crossword mode.