Hey man and welcome to the wonderfull world of painting!
First off, that is a very good level to start off with, and it's a lot better than many when they start. If I were to give any tips, it's that the miniature itself is all in the same hues.
Black, brown, brownish red, and that scheme works - But you need something to paint it up against. A colour only really pops when it has a contrast to work against. This is where I see the problem in your scheme, if I were to focus on something.
My advice would be to strike some more color in the ones you use. Make the black more black - The red more striking. Use the blue lens to give some stark contrast and make the model pop. Paint the eye slot in the helmet in the blue as well, to give him focus.
The colour combo works - You just need to emphasize it, so the model doesn't seem to muted. Don't be afraid to make it a bit more lively.
That's my 5 cents. You're on the right path man - Keep it up