C-a, C-e, C-b, C-f, C-p, C-n, C-v, M-v for line/screen maneuvering.
C-o for Ace-jump to go to the start of any words I see on the page.
C-d to delete.
C-s to search for words not on the page.
C-k, C-y, and also how to use them with paredit to yank whole s-expression chunks.
Buffer switching and killing.
File saving and opening.
I teach the above to any friends who want to learn Emacs/Clojure/LISP, leaving out a few other features like whole word deletion and more advanced paredit. With halfway decent aptitude and a little practice, they become productive very quickly (within a few hours, which is a pretty good investment relative to "normal" text editors in my book).
Also, you can use a lot of the commands for normal OSX text editing, which further improves the investment.