Today I began sculpting a skull from scratch in zbrush while at the same time helping a student in drawing to help see big, basic shapes of the skull and to think conceptually of the light (rather than following the actual light situation where there are multiple light sources canceling out the form). The main point however to think in terms of big shapes, to search out big shapes in order to be able to commit to memory to call upon so that one can draw from memory/imagination.
I did this in about an hour starting from a sphere.
I had talked about this in a previous blog entry: Anatomy Lesson.
And I had mentioned using plastic skeletons as an indispensable reference material in an earlier blog as well:Skull
The skull that I used was part of a full disarticulated skeleton that I had bought online.