On the patch to becoming a Gmail master, keyboard shortcuts are a major stepping stone. There are, however, shortcuts hidden from plain sight, including the "b" and "d" shortcuts for composing new messages with CC: or CC:/BCC: fields already enabled.
Gmail doesn't usually open up the CC: or BCC: fields until you've clicked the links to make it so, but hitting the "d" key opens up a composition window with a CC: field available, while "b" enables both CC: and BCC:. As the Google Operating System blog points out, you'll need to enable keyboard shortcuts in your settings to use these or any of Gmail's shortcuts (which you can glimpse by hitting "?").
Undocumented Gmail Shortcuts for Composing Messages [Google Operating System]