Ok here is what I say:
1) Show some options with the commands. For example ls -lah is a great command list -long, all (include hidden), and the size in human redable format. rm -rf (recusive, force) is another very useful command for removing directories or just toasting a number of files. cp -r and mv -r are also handy (-r for recursive)
2) df -h for disk free in human readable format.
3) explain chmod xxx. 1 - X, 2 - W, 4 - R.
4) commands to add: mount, umount, shutdown, reboot, less, grep, apropos, su, rpm, tar, lpr, and lpq.
5) Add options to the list. Don't be all inclusive, just common options (like my -r example) or stuff to make their lives easier (eg shutdown -h now)