Here's a snowman I have colored for Christmas cards.
I stamped him on whisper white cardstock (Stampin' Up) and colored only certain areas of his body with Prismacolor pencils: 904 Light Cerulean Blue. It's hard to tell in the picture but I put the blue in the shadowy areas or where there are "hash marks" on his body.
Around the outside of the snowman I used the light cerulean blue and PC949 Metallic Silver for shading.
ETA: I cropped the photo to see whether it makes the coloring more apparent.
Gallery at Splitcoaststampers