I’m not sure if this has been covered sufficiently already, but I’ve heard lamentations by various writers about the lack of a keyboard shortcut to bring up the file-tagging popup in the Finder. While none is provided by default, one can easily be set up.
In previous versions of OS X, the File menu had Label: followed by the row of colored cells. In Mavericks, the row of tags is still there, but the un-selectable Label: has changed to the selectable Tags…, which opens the tagging popup menu next to the selected file.
This process may already be familiar to MacOSXHints readers. Go to System Preferences