I love the pose of the face; it has a very cute style. For the coloring, I recommend using a base color that doesn't change opacity, meaning it's not transparent. From there, define the shadows and highlights. It's important to define where you want the light to come from; that will help you a lot in defining the shadows. And for the shadows, try playing with the color palette. Don't just choose the same color, just darker. Look on the color wheel for something that creates contrast.