Excerpt
To create the long, somewhat coarse texture of this mane, start by painting the darkest shadows, using a 1/2-inch brush loaded with two parts of burnt sienna and one part black.
Apply the paint in long, full-length strokes that start at the ridge and move toward the ends of the hairs. Use a soft, dry blending brush to trace over the strokes to blur and soften the edges.
Clean your brush and pat it dry and then use it to pick out color from the lightest areas. Use the edge of the brush and less pressure as you reach the ends of the hairs to create fine-pointed tips. Wipe your brush clean after every few strokes.