How to whiten wings with crayons and shadows [hand-painted]

Your crayons should be thicker, right? I mean, thick ones are easy to color. First paint the whole wing white with crayons, not too heavy or too detailed, and then handle the shadow with gray crayons! Or paint the exposed parts of the picture white, and the shadow parts can be carefully treated with gray crayons, and some places are even heavier! If you are not at ease, I suggest that the landlord simulate it on white paper now, and then color it on the map when you feel the effect is good.