HEAD DESIGN - some different approaches

When drawing heads for a character design, the number 1 battle is breaking away from whatever it is that you usually do.  It is essential to stay loose and not confine yourself to one head shape for all characters (see anime - this is a no no).  Remember the anatomical and gestural match from Walter Stanchfield.  Also, each character you design has their own personality and story - thus, they deserve their own shape and design!

In short -

There is no ONE way to draw heads.  However, whatever your process, it is ESSENTIAL that you know the basic and anatomical head structure.  Foundation first, if you don't know it you've got to learn it.
THE FOUNDATION: no excuses, there are tons of resources out there. here are some links
Andrew Loomis: Drawing the Head and Hands
How to Draw the Head from Any Angle

SCRIBBLES - Turning loose abstract concepts of shape into unique an un-routine heads. - with Ron Lemen Studio2ndstreet.com
OCTAVIO RODRIGUES - Making faces out of Shapes - "This process I find helps to keep you loose and also keeps it fun as you discover shapes you wouldn't normally create"
VARYING PROPORTION - how moving the eye line, adjusting eye spacing, you can vary the proportions of a head design. - varying proportion can apply to other aspects of the head as well. Ex: forehead vs. chin sizes, nose vs. ear, mouth vs. eyebrow etc.