Creating Highlights and Shading with Color

When using highlights and shading to light with colors, take for example the color yellow as the light source. It is useful to use a cool color (like dark blue) as the shadow color. Using the cool and warm colors in the image makes the image more vibrant and flowing. I learned this technique from painting. Also, don't be limited by just using the opposite color on the color wheel, you can also use proximal colors. For example, yellow has the light and purple as the shadow.