Make a new layer above tail (tail border): ctrl-click the tail layer, fill tail border layer with black on the new layer, go to select>modify>contract enter 5, hit delete. This will make a 5 pixel border around the tail on a new layer.
Step 17
Use the smudge tool on the tail and tail border, set the opacity on the tail border to about 75% and the opacity on tail to about 50%.
Step 18
Now we're going to start making the texture for the tail. Take a 1px paintbrush and draw some black lines on a new layer above the tail. They don't have to be perfect, or even straight. Just in the same general direction. Call the layer Tail Texture.
Step 19
Duplicate the layer, and put a color overlay of white on the new layer. Select the move tool and push the up arrow once, and to the right once. This moves the new white layer 1 pixel up and 1 pixel right of the black layer.
Step 20
Press ctrl-e to merge the white layer down to the black layer. ctrl-click the tail layer to select it, and go to select>inverse to inverse the selection. With the Tail Texture layer selected, press delete to get rid of extra lines.
