I did this tutorial ages ago for a friend. But now that I'm done with this particular style, I don't see any reason to keep my methods secret any more

So yeah, this is pretty much how I do my comic shading for Phoenix Requiem. It's not a detailed tutorial; it presumes you're already good with Photoshop.
Edit: Obviously, this image is a couple of years old. I do things a little differently now, but this should give you a rough idea, at least until I replace it with something else

Did you also do the linearts for the dog? I really like with how less lines you give all the information about shapes and forms, great stuff.
Finally, I can go back to coloring with grayscale like good ol' pencil and paper. TT uTT