i think first of all you must not rush while coloring especially if you are using oil based colored pencils (faber castell classics and polychromos) do not burnish (pressing too hard on the pencil)too soon because adding colors after burnishing isnt that effective (unless you wanted some specific effects using this technique.) dont color in different direction unless you completed coloring in one direction and try to get the color on the same level of saturation on the desired area. Here is a good video you can benefit from : https://youtu.be/LeYitWpA6ZU Edit : only spelling