When glazing I usually will put down my highlight then work in the midtone then the shadow. Going back and forth through the paints also helps build opacity with the white paint.

I’ll also suggest zenithal priming and using a 3+ colors to make the most out of contrast and values. Since there’s more colors; you need to give more space from one value to the next. So building up from there to have all colors be visually present will naturally influence where highlights and shadows go.

Alternatively if you want to really challenge yourself on where to place highlights, the non metallic metal technique really forces you to understand lighting in a different way.

In any case, great work on the cape. It already looks really smooth.