The stylus was a battle to figure out, with the multiple layers, highlights, and shading. The speaker holes are of varying sizes and fan out from the left to right, and the d-pad and stylus are both within the lower 20% grayscale… to mention a few. 
When you get down to the lower end of grayscale, a lot of the shades fall outside the 8-bit color gamut so 30% become something like 18 levels you actually have to work with. (And the only way to do it is with trail and error.)
I did happen to learn a new trick or two, so that is good. 
I may also try adding some texture if I can find some high res photos to be sure… film grain can look like texture.