Try not to smudge the render, unless the rest of the sig is smudged. And if you do smudge, make sure to put scatter settings on at the least and get a good smudge brush.
Also when putting lighting, try to put it before the gradient(if you used one). Because the pure white lighting with the rest of the sig looks a little off. Also use a 300px soft brush not a 100px.
KIU tho, eruption.