Change your piece to greyscale, and squint your eyes. Are the values of each area distinct, or are areas blending together with others?
Pay attention to the shapes created by the value in the piece. Are they interesting and dynamic? Do they tell the story or sell the emotion well?
Is there a clear focal point? Make sure there’s a clear focal point, even at this stage. Focal points are for ranking information – consider having a primary, secondary, and tertiary focal point.
Are your values consistent with the light and the material? We are seeing values created by the local color + the light. What will the local colors be? How does the light affect those colors?
Is the core feeling clear? The core feeling should be fairly clear, even at this stage. What can you do to make it even more clear?
Do you need to simplify your composition? Try shapewelding – combine adjacent shapes of similar value or color.
Do you need to start with two values? Where are the dark areas? Where are the light?