Use the keyboard shortcut [Ctrl]+[Alt]+I to toggle back and forth between your document and Print Preview.
I like to keep my fingers on the keyboard while working -- avoiding mouse clicks whenever possible. It isn't right or wrong, it's just how my brain works. I just ran across a great keyboard shortcut for toggling between your Word document and Print Preview.
The truth is, Print Preview is already only a click away. Simply click Print Preview on the Standard toolbar. Or, choose Print Preview from the File menu. A toggling keyboard shortcut hardly seems worth the trouble, unless of course you prefer the keyboard! I like this one because it does double-duty, toggling between the two views.
Simply press [Ctrl]+[Alt]+I to toggle Print Preview and the document.
For whatever reason, this shortcut isn't listed to the right of the Print Preview command on the File menu.