
http://www.appletell.com/apple/comment/top-15-leopard-hints/
Okay, this is quite old, but I stumbled across it, and it might give newbies some good tips.
Although, the most useful I've found is Auto Remove Printer after Print. This has always irritated me - having to quit the printer app every time you print something. Well, all you have to do is right-click on the printer app when it's in the Dock and choose "Auto-Quit".