For this piece I focused on lighting, color, and texture.
I started out by loosely striking out the shape and colors of the mane (and ear). Then, I did the same for the face. The third step I adjusted the proportion of the face to the mane and added the nose, mouth, and the spot for the eyes. Finally, I focused on details and adding contrast to the lighting.
(Fun fact: I always believe eyes, and specifically the highlight on the eyes, add the life and spark to a painting.)