Over at 43Folders, Merlin has been soliciting tips for command-line beginners. I started to post something in the MT comments box, but why not post it here instead? With that, my random tips:

Learn about command-completion and history features. These save a tremendous amount of typing, prevent all kinds of stupid errors, and generally make you feel like a whiz. For example, to list the contents of the Applications folder, type ls /A[tab][return]. Cool, yes? History keeps track of the commands you've already run, so you can call up the last thing you typed and edit it for example. History is generally browsed via the up and down arrrows.

Play with things that cross the GUI-CLI divide, such as typing open . in the shell to open a Finder window showing the current directory; or the "Open Terminal Here," "Run Terminal Command Here," or "Run Terminal Command With" commands in LaunchBar; or their analogues in QuickSilver.

Explore fun hidden stuff in the shell like the /usr/share/calendar files or the cal command.

Get a feeling for how grep works with experiments like grep '^foo' /usr/share/dict/words or grep 'a.*b.*c.*d.*e' /usr/share/dict/words

Type >console in the username field at the login screen and you'll go directly to the shell.

Copy some text to the clipboard and type pbpaste | say

Read manpages, but also Google the name of the command plus the word "examples". Unix manpages often suck when it comes to providing examples.

Have fun. Take small bites. Don't worry about learning it all. Nobody learns it all.