Here are a couple of techniques I use when learning to render with a new medium. The color selection stays small. Only two hues where used in this image, red & green which are complimentary to each other. Also added is cool, warm and brown tones. They each have a gradation of value.
I will also take time while I am rendering, to create a color chart. This includes a color sample color and it’s Copic number. This chart is a great reference for me as I am seeing how the marker color looks on the page.
Quick note on creating contrast in this image, I was careful to render the desk with a very light value and without any texture or pattern. This creates a high contrast with the flooring and wainscot which surrounds the desk. Notice these architectural elements have a darker value with rendered pattern and texture.