Well, If I were to make an entirely new head, what techniques are best to keep the triangles to a minimum?

What I do:
I loosely follow the tutorial I linked to in the first post.  That is, I make a cube, extrude it into a basic head shape, and subsurf it.  But then, when I do my fine tuning, I select groups of vertices and subdivide them.  This creates those pesky triangles.

Is there a method other than subdivision to make small details, etc.?  Or is there a way to use subdivision while not making triangles everywhere?

Thank you so much for your help.  :)