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ooooh your shading style is really nice, though in 1 it looks flat and needs more contrasting colors, I really like 2, and 3 has some really nice colors for the iris
#3 is really nice except the pupil is much too bright, try giving #3 the pupil from #1.
Something to help out
Im guessing he meant the iris, it is pretty bright, to the point where its unrealistic. The iris from the 1st eye is great, like really great, try doing something like that maybe
Your shading is actually spot on, although you position and draw the eyebrows a bit weird I would suggest you outline the shape first then fill it in and then add in strands in a darker color, maybe try and add in some eyelashes aswell and keep the eyebrows a bit higher up. This might help
Something to help out
PS, love your art man :o