I think your linework is decent, but they all feel a little bit rushed. I think you might find drawing way more fun if you think about your drawing as a 3d object, and identify where the shadows/highlights should be, rather than thinking "sun is left, bright spots must be left side and dark on right side".

and think about the light source, is it harsh sunlight which will create hard shadows, or is it cloudy outside, creating soft shadows?
Is it warm light or cold? is it perhaps multiple lightsources creating lights on multiple sides of the character?
You should think about warm and cold colors instead of shading in gradients of black and white, like the example below. You see that both the highlights and shadows arent completely black or white, and they all follow the rules of color temperature.





So you can create contrasts in your image this way, instead of using white and black, shadows are rarely pure black, its just a dark variation of a color, like dark blue per example. You see the darkest areas in the paintings above isn't even close to completely black.

Thinking like this might greatly help you and you will develop as an artist.

This also applies to cartoon/anime drawings.

here is a nice example.