I draw while I work, really, at home I never have the time or patience for this painstakingly shading. That's why I don't use refs... my colleagues aren't willing to pose ^^
Photographs from stock artists are always available and there are many tutorials that feature proportion and anatomy out there. Devaintart is loaded with resources that may prove helpful.
Again in my defense... I have no internet at work. I work at work, and draw while I talk to customers on the phone. It's therapy! XD
Ah well, I'm proud at the tail and the details at his middle. ^^;