When Polygon modeling, what is the best method for transitioning between areas of large mass to
areas of smaller mass and still maintain all quads? 

Best is not defined, sometimes its actually impossible, but in general what you use is circular structures to overcome this problem. Theres no generic method for this tough as we dont know how to evaluate such systems mathematicaly in way thet lets us solve teh best way. Good too because otherwise many 3d artists would be out of a job.

Thank you! Do you know a good tutorial, website or book that would show me these methods?