Something we all need to save time:
http://www.lagmonster.org/docs/vi.html
And if I sum it up with most useful commands and other tips, here are my favorites:
In non-editing mode (press esc to come back to that mode):
/text_you_want_to_find
$ to go at the end of the line
Set vi as the default editor (for crontab etc.): add “export EDITOR=vi” to ~/.bashrc