The concept for the picture is pretty good. I can tell what youre aiming for.
The neck however is too large. Try downsizing it a bit.
The effect I think youre going for would work a lot better if you used a cooler shade of blue. in the background.
And you should try for line depth. If you had better line depth, it would really help for the emphasis on the horn.

Overall, I feel like youre a begginer artist whos honestly trying, and I like to see that !