I'm working on drawing realistic faces, so I can get used to those proportions, and to do that I've been drawing from references. Problem is, I can't find that many pictures that just focus on the face! So far I've been practicing with myself and my family, but I'd like to expand some more. Any suggestions?
Draw with a little mirror on your desk so you can use your own face as a reference. This helps not only when you're trying to learn how to draw faces, but when you're trying to draw certain facial expressions---you've got an unlimited resource stuck to the front of your head. ^_^
Facial Expressions: A Visual Reference for Artists and Facial Expressions Babies to Teens: A Visual Reference for Artists both by Mark Simon are great books to have. Of course a camera and a mirror will always work if you are desperate also.
I need to add them to my list of recommended art books I've been keeping on my DA page now that I thought about it.
Well you can use your friends photos that you take of them, dA's stocks and resource category in portrait mode which has a lot of them, stock sites like sxc.hu, take pictures of your classmates, strangers on road..
Try googling images of say "scream" or "sad" and use the filters so you only search for large images then make sure you checked the Face filter. If you can't find the image you're looking for, broaden your search. Hope this helps!