My favorite of Leonardo da Vinci's paintings is Lady with an Ermine. Mona Lisa's got absolutely nothing on her beauty. If one was to really paint like Leonardo, they would paint on a much larger canvas (this is a miniature 5" by 7" canvas), and start with an underpainting of a thinned color such as umber. Then they would paint many layers, letting each layer dry especially in the glaze phase. When glazing, the "sfumato" method, meaning smoke, is used to very subtly shade with very thin layers which darken the layer underneath.
