Very nice! I actually quite like the 'dirty' look to it, it's got a nice feel to it. Good to see art of Knuckles! Sadly, I feel he hasn't been as appreciated or recognized in recent years. It's a shame, he's a great character!
I'm actually somewhat serious about the whole teach me thing, I happen to be an aspiring animator. but before i can even go into the mass fun of 3d modeling, i've got to be able to draw the concepts behind them! XD. So I ask: ya wouldn't happen to know of any programs (besides gimp) that might be able to help me out would ya?
The way I learned is just being consistent. You keep drawing what you want to be able to draw in different situations or positions. That and of course I did art courses. Currently in college.. But anyways like I don't know any programs just methods. My apologies.