The head looks really cool
It always seems hardest to get the lines right on a car mode for a custom. One the Krylon(white in this case) has dried for a week what I've often done to get the straightest lines I can is simply mask the area wanted as the base color with scotch tape before the brush work. I've had some success with that, though at times a stubborn custom hasn't cooperated as well
I really like how the white came out. Nice job.