I wrapped a grid around the arm following carefully the actual shape of his muscles and skin. The grid helped me to place the scales in correct proportion.

I applied color in each section to indicate the scale changing the color as I saw on my photo reference. Note that all the scales are not the same size nor shape. Having some of them less round, more flat or smaller helps with the overall perspective of the arm.

To keep a clear separation from the back of the arm and the body I used an electric eraser to lift out color also creating a stronger highlight. Did the same with the claw. That worked well because the background behind the claw is dark. I did not put much focus on the scales on the body just mainly on the head and forearm because they are closer to the viewer. It was also necessary to place some darker colors on the body behind the arm to make clear the separation from the arm and body. The darker contrast pushes back the body while the highlight on the arm brings it forward. Remember dark values appear to recede into the back or deep places while and lights appear to protrude or advance toward the viewer. Yes, we can create illusions in art to make our subject more believable.

I continued using my dark colors in the deeper places around each scale.

And that is how you develop the scaly texture of a lizard. it really was a fun project.

Here it is the finished project, my colorful Iguana. Isn't she beautiful?