For coloring, make lighter colors fade to yellow and darker colors fade to blue. Just like if you look out on the horizon in the real world, objects further away will get slightly more blue the further away you are. In pixel art, this can be exaggerated for readability. With this in mind, here's a gif of my palette selection process:
The colors were compressed, but you can see generally what I do. I'm no expert but this gives nice results most of the time. So, more towards blue, and I also desaturate the darker colors more. Without touching the pixel work at all, I changed the colors of your sprite:
I'm not great at pixel art by any means, but I hope that will help the sprite stand out more. Also, I'd cut back on the dithering... but don't feel the need to add more colors.