Nice work! the only things that bug me are the lack of shading on the gun and the color pallette.
Try using Higher contrast between the two greys on the pants, and shift the hue a little between the two yellows in the shirt (higher contrast there too). After doing this, you could try to replace the black of the inner outlines to a darker shade of the color of that area
EDIT: I see an unhappy reaction. Sorry if it came out as preachy, I didn't mean to discredit your work. Maybe my suggestions dont really fit with what you were going for. I'm gonna add an half star for encouragement
༼ つ ◕_◕ ༽つ★
(and also a ticket for a free roast as soon as I dare to post pixel art here on newgrounds)