You have a nice idea going, but I noticed that your image looks a bit chalky for a few reasons. One of which is you have to learn to use larger brushes and map out your volumes before going into details. The other reason is that you don't have color mixing quite down. Areas that look more dulled out or chalky are the shadow areas where you couldn't decide what color to use.

Try not to render every hair but try to get the major forms of the hair down first in blocks or clusters.