Pistachio ninja'd me but here's what I was working on. His edit is dynamic, super tight and I actually recommend you rework your piece based on those ideas. Meanwhile I tried to stick to your style, so here are some ideas that will be easier to transfer:
My thoughts:
You have a lot of stuff fully lit, like the left side of the tiger's beard for example, that couldn't possibly be lit without reflected light. Since there is nothing in front of this woman, there is no reflected light.
Dither, especially at this resolution, is very powerful—too powerful. It's just pure noise, you may as well save as JPG if you're going to dither so much.
Instead, and please try this from now on, focus only the volumes! Define your forms carefully—and only at the end, if everything looks good, sprinkle on a bit of dither as texture. It's like salt, and you've got too much of it.
When I reworked the shield and the cat's right arm, I had no idea what was going on. The forms are poorly defined and cannot be read, which makes them effectively noise. Rework them so they are clearly understood.
You're rendering from a "up is light, down is dark" paradigm, which is true in most cases, but the reality is "near light source is light, away from light source is dark". Of course the only source here is the moon, so the left side of the cat would be in
darkness, there is nothing that could possibly light it.
Highlighting the edges of the rock is both possible, since the moonlight could reflect off it, and helpful, since it further distinguishes the subject—speaking of: is the moon your subject? I'm guessing no. In which case, push it
back. It is competing with your subject for attention, and at this point it's almost winning.
Lastly, a little theory. You know that every pixel represents something real that occupies that space. So consider the hair: if the hair is white, the pixel is white. But if the hair gets thinner, then the average color of that pixel becomes darker, since some background is showing. And so the thinner the hair gets, the closer the pixel gets to the background color. The same is true if the hair recedes in space, same effect. So take a look at your hair strands and consider what they're implying.
