You've clearly got some fairly decent painting skills. You need to work on two things: technique-wise, smooth-blending is your next port-of-call. Look up how to make a wet palette, as this will help. You blending on this mini is jerky and has obviously been disguised with a number of washes. Secondly, you need to start studying colour-theory if you want to reach the next level: composition is the key. Two miniatures, painted with identical skill, can get wildly different scores, because one is well-composed and the other is not.
Its a nice job. You did some cool effects, esp on the face mask and exhaust pipes and gem. But where you need to work on is more accurate and deeper shading and highlighting. And Dull-Cote.