Cut different not painted parts of the source and paste making a higher wall. Mask the borders to blend
step 2 of 6
Make the budy's hair cutting and warping the horse's hair
step 3 of 6
Draw two shapes, one for the skin and one for the clothes.
Apply the fur texture to the clothes, use the shape layer as clipping mask
step 4 of 6
In a new layer in multiply mode begin to paint with different tones of brown, use the smudge tool and the eraser to blend.
Use as many layers a necessary to get the darker tones.
step 5 of 6
Separate the budy's hair in two layers, use image > adjustments > Brightness/Contrast to make one look older than the other
Make a new layer in overlay mode and begin to paint the highlights with a soft brush with white, use again the smudge tool to blend
step 6 of 6
Draw the general shadows, paint also over the drawings with some vivid colors.
Continue improving the shadows add some general light too