Bram Moolenaar, main author of vim, has written (quite some time ago) a very useful article which shows some good ways to use your favorite editor (vim, of course, but most of the tips also apply to other editors) more efficiently.
Besides the generic tips and tricks of text editing, the article also mentions some specific vim commands, e.g.
CTRL-N (word completion),
% (match braces),
:abbr (prevent typos), and many more.
Oh, and if that's not enough for you, check out a few hundred vim tips over at vim.org.