i was using a soft round brush at about 9 pixels to paint with. Now i make the brush 53% opaque, and start working with strokes into the light and dark areas, blending but letting the strokes suggest the strandiness (is that a word?) of her hair. i never use a blur or a fingerpaint (smear) to do this. This further models the hair. See, you can feel the weight and texture of it this way.