Lines too thick:
Be very careful with expressions- esp eye area. Squinty eye: Make sure we know which line is the closed eye, and which is the wrinkle. Don't confuse eyebrows with eyes or eyelashes.
Don't forget details- like the line for his nostril.
Lines too thick: Always be aware of the shape inside the borders of the lines. When the lines get too thick, they can eat up the shapes inside-like the feet hands, eyes
Can you find some way to simulate drybrush for the zip effects? Rather than hard lines.
Avoid parallel lines like the plague.
The stripes on his shirt should wrap around his body, but not be perfectly evenly spaced apart, nor the exact same width each.