Shadows study

Ok , here is something to illustrate my shadow tutorial.
[link]
In this case , I am using a great line art from

when I do shadows , I like to paint the black over a white flat.
it gave the image a statue look , and its very easy to see if the shadows are on the right place .
you can see the volume and the projected ones clearly this way

try this .

find a line art that you like , make a psd file of 3 layers.
Line , shadows , and BG
choose a light source , put the opacity of the shadow layer to %35, and use a pure black brush at 100%
have fun , and send me a link to your work .