Ever noticed how some coloring pages look flat but seem to pop out of the page?
Its always a good idea to use multiple shades if you feel comfortable to! Using multiple shades will elevate your art by enhancing the natural shape of the objects in the scene.
When using multiple pens its always easiest to start with the color you'll use most of. In this case that's light stone first, then dark features after.
Make sure to leave spaces between the stones for the moss in STEP 2.
STEP 2. Light green first, add darker details last.