Work in silhouettes
Block the main forms with a few flat tones. Check whether their overlap and scale explain the scene. If the image is unclear at this stage, detailed rendering is unlikely to solve it.
Choose a light direction
Apply one consistent direction to the largest surfaces. Compare cast shadows with form shadows. Keep the light understandable before introducing reflections or secondary sources.
Add texture selectively
Use surface detail where it helps describe material or direct attention. Leave quieter areas around it. Save stages separately so you can compare the final image with its simpler structure.