Some crits:
I am unsure where the focal point of your picture is, the character is too close to the edge imo. What is the character doing, why is he there? Don't know what his outfit is for either. I think you should try making a small thumbnail where you figure the composition out first before you start detailing the piece, I made a quick thumbnail to illustrate:
I assumed that he was going to catch fish using the spear, I also limited myself to 3 colors as well, I remember reading somewhere that its a good idea. I'm not really an expert in composition but I hope this was helpful
