Okay, here's a good tip... when doing pixel art, it's best to work with a mid-tone grey background.
Problem with white is that it'll make your colors look darker than they actually are, and strains your eyes to focus extra hard to look past the blindind white to focus on the details.
I also wouldn't recommend working on black or colored backgrounds too unless they're actually part of the picture.
If it's just a sprite you're working on and will be placing it onto a desgined background later, definetly work on a mid-tone grey first.
As for your artwork, not too bad. The shoulders are a little too high. The lower half of the body is too small for the upper half.
Fire is generally mainly orange and yellow. Some red in there too if it's a big fire. So I suggest you change your fire pallette.
The inside of the coat would work best with the darkest blue tone. And add a mouth to the face.
The sprite overall could use some touching up here and there.
Also I noticed that there's a bit of saturated blue on the right side of the coat (our right) which seems to have accidently got onto your sprite.
With all that said, the look of the character is good otherwise.
