If you are an excellent typist you may prefer to use the keyboard rather than keep stopping to use the mouse to select a ribbon button
If you press the Alt key from any ribbon, KeyTips appear. Press the relevant key to access the ribbon or command required.
Further letters appear giving shortcuts for each button. Press the relevant key to activate the button; if there is a dropdown further letters will appear to allow further fine-tuning of the command.
If you are upgrading to Microsoft Office 2010 or Microsoft Office 2013, you may be interested in upgrade workshops and floorwalking.