Also note the colors of the shadows. Painting a shadow doesn't simply mean you put some black on a brush and dab it down. Shadows have color (for more on this, read What Colors are Shadows?).
"But there are bits that are black", I hear you say... Well, I still wouldn't paint them with black from a tube. I'd mix the darkest orange/red I'd used in the painting with a dark blue (its complementary color), such as Prussian blue, as this gives a much more interesting dark.
