The .emacs file
The Emacs Lisp language
The built-in help system in Emacs provides on-the-fly help pages on functions (C-h f), variables (C-h v), and other Emacs Lisp concepts. See C-h C-h for an overview of the help system.
The hefty PDF versions of the Emacs manual, Emacs Lisp manual, and Chassel's tutorial describe the Emacs Lisp language in great detail. Download them and use as an overview and reference when something is confusing.
Perhaps the best way to make your Emacs working environment more efficient is to borrow ideas and code from other users. A web search for "dot emacs" or "my emacs" returns many examples. Here are links to mine:
Note that they're machine-specific, so you need to adapt to your machine and personal preferences.
ADMB-IDE comes with a .emacs configuration file that has some unusual settings worth checking out.