Working in layers, you can create a lush, soft effect in colored pencil that can create truly stunning coloring book pages. In this post on the Craftsy blog, the artist offers a tutorial for how to build layers slowly, with one color at a time, allowing for better control over value and consistency of color. A little bit different than working with several colors at the same time on your piece, the results are luminous and stunning.
I can help you out with that! I have gone ahead and collected over twenty tutorials to make your coloring even better. They are a mixed grab bag of coloring gems, sorted by the type of art supplies used. That should help you narrow down your range of options, or see what potential other media hold.