I think I can see how you "Failed" which is not to say you did a bad job! You did wonderfully! But here's the difference. If you look at the shading the comics, they either do a hard line, such as in the covers of Sonic the Hedgehog Issues 195-197, or VERY gradual shading, not a combination of both as you tried here.
I'm sorry if this is confusing, I'm no artist, but I noticed your own criticism and I don't like to see that, so I wanted to help you improve your art (much better than my own) in any way I can.
Nice work!
I'm sorry if this is confusing, I'm no artist, but I noticed your own criticism and I don't like to see that, so I wanted to help you improve your art (much better than my own) in any way I can.