Add global lighting, add local lighting, reduce local contrast. Quick little edit to try a few things out, needs a ton more work of course.

I wasn't asking about this piece. I was asking to see a few pages from your sketch book, so I can gauge your drawing skill better. Pixel art is too rigid to show artist's intent, so I usually ask for some sketch book sketches to confirm suspicions I have about technique and skill and such. It's also a good way to find out which exercises can help you get where you want to be. At your level of skill, most of your practice should probably be done on paper anyway, only jumping to pixel art to make the final pieces you want to create.

For example, you might want to play around with volumes and sketch a few dozen sketches trying to figure that out. Then you can study mechanical parts you like with that knowledge of volume. In the end you put it together by doing a few silhouettes of robots until you get comfortable, and then do a couple full robots to get the hang of how they work. After all that, you open your pixel tool, and pixel a robot.

I'm a pretty decent artist, but if you were to ask me to draw a robot off the top of my head, I probably wouldn't fare much better than you at first. I'd want to at least do a few pages of sketching and trying out things before attempting.

Does that make sense?

I feel like everything is fighting for attention. There's no global light it seems and there's no local contrast (everything goes from really dark to really light). I've been looking at the image for a few minutes now and I've already got noticeable eye fatigue.

Someone's a big fan of Another World I see

As it damn well should be!