The image above is from a class taught by Glenn Vilppu I took a little bit after all that watercolor experimenting was done. The head drawing class showed me I know nothing and have so much to learn. It was a wonderful feeling, starting out as the least talented in the class but with his amazing guidance growing so much from there. Rather then posting all the heads I drew, I'd rather link to TheBulfrog's Book on ConceptArt.org where I kept an ongoing thread of my work for over a year. It has 100's of my sketches as well as many not found anywhere on this site. It shows some heads from earlier classes.
The head pictured above was a major breakthrough for me, as I started to feel I was getting it. I now know how far I still have to go, as the most important part of any drawn head is getting the expression and the tilt, no matter how loose or cartoony the drawing is. This class got my heads looking much more realistic, but I still have a ways to go before I start really internalizing those two crucial requirements.