I agree with no shadows, although I wouldn't mind seeing you take a shot at a sort of sun dappled cell shaded effect for cloud shadows, as opposed to...
Hey bovey - I'm sort of in agreement with the people that suggested a variation in color, so I tried a super quick and sloppy overpaint. By no means...
Dave Johnson has a blog where he did some takedowns of what he felt were poor covers. He also highlighted what he thought was good. It's worth a read...