Shading is very hard to master, especially when you have a very complex shaded image that you need to clone. I had to recreate the dog of the Schmackos dog treats box, i found it extremely hard to get the shading right. I discovered a simple way to get the shading right, i pasted the original image in illustrator and vectored the image, i then pasted it into photoshop and locked the image. i then locked the original image behind it and lowered the opacity of the vectored image. I locked both together, made a new layer, and by using a white paint brush i highlighted all the areas that needed it, i then used the eraser tool to shape the highlighted areas. i made another layer and did the same the shading, using a dark brown paint brush. I made a few different layers so it was easier to control the small the lighting and shading to the larger.