Here are a couple of tips for beginners. These can be applied to most of the programs in the fcp suite.
Explore the menus. If you don't understand what something does, look it up in the manual or the online help.
Explore contextual menus. Control clicking (or right clicking if you've got a multibutton mouse) on many items will bring up a contextual menu which will allow access to bunch of handy shortcuts. In FCP, try control clicking on clips in the browser or in a sequence, an item in the track patch panel, the timecode track of your timeline. All sorts of neat and useful stuff becomes available.
And remember that the help menu in fcp provides access to a searchable version of fcp manual.