I don't knew at first tha tit was a monster from Monster hunter, but as I recoginized that I searched myself some references.
The main problem is here that as well forms as color aren't really fitting together with the creature concept. I don't know your reference (link isn't working) but the proportions were also off.
I'd suggest that you should start with correcting some colors and create a palette which is interconnected in the whole image to get a homogen color look. then you should look carefully how the whole thing is looking, I don't played the game so I had only the rough imagination of some pictures.
As long as your proportions and your basic forms and colors aren't right you shouldn't start with detailing the stuff. Work at first sloppy and refine always the picture as a whole, this brings usually a better result than detailing part for part. Of course if you are fine enough you'll have to give each part the final touch.
I also played a bit more with the light. Its obviously coming from the left side now. I also added here and there some reflections from the ground and I also did a bit more with the wings.
I don't detailed anything yet, the head was done with a bit more attention, but it's just an tip in which diraction you could go.
It's also rather big for a pixel art piece. Maybe it'd be a good idea to study some good pixel art revs.
Here is a suggestion for some important changes while staying pretty near to your version.