This is a brief summary of mine of those Emacs commands I have found useful over the years ... I hope you find them too.
An (old but still useful) official Emacs Tutorial (obtainable via [C-h F] within Emacs)
The (old but still useful) official Emacs FAQ (obtainable via [C-h t] within Emacs)
Technical and quick reference in two pages (version 20)
Enjoy!