Thanks a lot for your comments. Please note that although I searched for inspiration on a well known piece from the site(And a great one, for that matter), I specifically tried not to use the same technique(And even not the same pallete, so I could to try harder to develop my own method, and hopefully learn something in the process). I tried to mix the colors not to achieve new ones(Witch is much harder on a small scale and with less saturation), but to try and achieve a "boney" texture, and overall make the piece look less "plastic". Anyway, I'll try to inprove on that, and maybe adjust some parts that don't quite fit what I was looking for(The green lines on the upper side being one of them)

Yes, the anatomy looks terrible :( . For me, particularly the unaligned cheeks, the teeth, and the nose. I'm trying to improve on that, too(Practice makes perfect, right?).

Agreed with felchqueen. Even if you've gone a slightly different way than your inspiration, the main problem here is the lack of correct anatomy. Doesn't matter whether you're using 3 shades of bone colour or RGB - it ends up looking weird if you haven't really studied and practiced the drawing of skulls.

I don't think you've studied your inspiration enough, you've clumped the colours together (particularly the blue) so I don't think you're going to get the effect you desired. A good attempt none the less.:)