Line weight variation - where lines closer to the light source are thinner than lines further away from the light source, which gives an illusion of depth to a 2D line image. While many artists will put black shadows straight into their linework during their black-spotting stage, in addition, some (like those who have mastered inking) will indicate that depth mostly with the thickness of the line. Also, this line variation lends a bit more visual interest to a black and white piece - and if a black and white linework piece can hold that much interest even before color is applied (looking more lively than your standard coloring book page) then it'll be that much better when color is applied.

Check this link - [link] - it's a bit more geared towards animation, so the outline becomes the heaviest line, which isn't try of all line work styles, but at the same time, his inking still has width variation in the outline.

In comparison, right now, just about all of your lines have the same thickness and weight. It flattens out your images to the dimensionality of coloring book pages. Granted, your color tries to compensate for that, but your work would pop a lot more if you did this earlier in the process.

I know you're trying to just swipe from stills, and you indicate that as such. And some of those shows have very non-varied line weights (it makes it easier on the animators), but since your drawings are static, you can spend more time playing with the lines.

Let me ask - is drawing a hobby or a profession or aspiring profession for you?

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