I think the first thing to ask before trying to teach them something is "what do they want to get out of learning Emacs?" AND, are you trying to sell them on the idea of learning Emacs or are they already committed.
If they are a programmer and are looking for a new development environment, show them ECB, how tags work, etc? If they are looking for a general text editor, show them M-x re-builder. If they are looking to write documents quickly and publish them eventually, show them org-mode with HTML and LaTeX exports.
