I was trying to follow along with Ryan Kingslien’s book on Realistic Game Characters – trying to sculpt a head – and I notice he says he used the trim dynamic brush to establish some basic planes of the head. I tried to do the same and ended up producing curved planes that were flat in one direction, but still maintained the basic curve of the original sphere in the other direction. They were not true planes, like he had.
Is there some way of brushing up 
on my basic brushing/sculpting skills? Is there some sort of tutorial that goes into things at a low level – just how to make flat regions at the right location and orientation on a sphere – stuff like that?