Hi, I hope you dont mind but I made an edit, it was easier for me to just give you an edited version of your piece than it would have been to give you a long winded explainations on some of things your doing wrong/badly
Firstly, I had never heard of this character or seen what he looked like until later during the edit I decided to pull up a reference, so bear with me
.
I dont recommend you take much away from how I did the creases in the clothing, as it is not that great, What I do suggest is you take a look at the detailing on the boots, face and hands, and also take note
of the colours I have used, how they differ from yours (I noticed your colours are quite saturated, this is bad for the eyes).
I didnt finish the edit as it was taking too long and I have things too do, but here I hope you learn something (anything?) from this.
Oh and a metallic material isnt too hard, metals have strong contrast (i.e. dark shadows and really light highlights) you just have to focus more on where the light is coming from and how it would react to a shiny surface (also, most metals are highly reflective so if your feeling brave
).
In my edit I didnt really complete the metallic effect, I just drew in some strong highlights to show what i mean.
EDIT: Oh! my bad, I just realised what he is doing withhis hands... lack of appropriate shadows brought this on I assume
Best of luck