Some quick variations on line treatment.
Upper left is the original, upper right has rounded edges for head and smaller eyes but eyes are same,
middle left has smaller lighter lines, middle right has brush tool for outline
lower left has a darker skin for the no outlined eyes, and lower right is not as noticeable but has texture overlay for lines
If you have other ideas for how to go about it feel free to post and we can all decide on one together, just make sure that its a reasonable method that won't take forever to complete.