Underpainting

   Underpainting is basically adding an opaque color to the base of the painting; much like building the foundation of a building before constructing the building itself. Usually a thin layer of white is added to the pre-draw on the canvas. Just filling in the spaces and outlining the lines. Then you can layer on other colors, mostly blue or purple to show lighting. The final layer is the real colors of the subject. Experiment with underpainting and it can transform amateurish paintings into a bit more like the professional ones.