Establish accent colours
Building a digital illustration on a pencil drawing lends a great traditional feel, but pencil lines on every inch of the canvas can make things look unfinished. I paint highlights above the pencils on Normal/Screen layers, with a gold gradient over the background to highlight my character. But this makes it too smooth. To restore some pencil texture and warm the colours, I copy my pencils to a new Multiply layer and colorise them yellow.