Tribute (step by step)

I was asked by to tell how I draw this-specifically the line art part. Well it differs from work to work but I can try to explain.

>I usually draw with digital pen a sketch.
Sometimes I use the pencil drawings I had but then I have to scan the image, level the colors(Ctrl+L) so pen lines get darker and background gets white. And after that I usually just over draw a digital sketch anyway.
>So I leave the sketch in 1 layer and the painting one I start on a layer on top. I usually only use 1-5layers, if I get more I merge them together. My motto is if you drew something once you'll be able to do it again. I don't use "undo" or "history" too much as well-takes up computer resources.
>And I just paint over and over the drawing on 1 or two layers.
I usually keep 3-5layers:
1st: the original sketch-to have a remainder of the original idea.
2nd: the painting itself
3rd: (sometimes the character is split from background-but I don't like separating them)
And the rest are some newer ideas or tests.
I happen to have base painting on layer 2, then a new sketch-with more detail on layer 3 and a second painting layer on layer 4.
That I do when I want to try out maybe a different thing-like face angle, etc but am not sure it will look good, so I paint it on a new layer and when I'm done I ether merge it (if its good), or delete, change if it doesn't look the way I want it to.

Hope that helps a little, this isn't really a tutorial so I can't help much, but if you have any questions feel free to ask and I'll try to explain.