I’ve just posted a handout on working with Microsoft Outlook Favorites in the Resources section, but you can grab it from here also:
At the top left of your Outlook Mailbox list there is a section headed Favorites. A little known function is that you can add Mail folders to this area so they are easily accessible. This saves you having to scan down the Mailbox Navigation Pane to find a folder you use frequently. Adding a Folder to Favourites does not remove it from the Mailbox list.
Get the full handout: Working With MS Outlook Favorites.