I've seen 2 of your works frontpaged now and haven't seen any suggestions or criticism on them. So I'm going to be brutally honest here. Retro style pixel art can look amazing but in my opinion this does not. I find your pixel art to be amateurish. Your colours are very basic and don't work well together. You don't want to overuse colours that are too obnoxiously bright (those colours that you see in the default ms paint pallet = Bad). Many things look out of proportion and some parts just look badly shaped. In pieces like this, when line work looks too sharp or oddly shaped, you can use slightly lighter colours around it to give the impression of anti-aliasing and reshape it. lastly you are abusing pixel dithering. the over-dithered look is a pet peeve of mine. I suggest exploring and practicing other shading techniques and using dithering more subtly.