I like to use chibi paint for linearting, because the lines are smoother I have tried Oekakai shi painter, and i dont understand how the people here understand it or get good pictures with it... D: chibipaint is much more like the previous software i used, gimp. it has really smooth lines for lineart. I would try it out. :]

also, use a 1point brush and don't sketch, use a continuous line to make it smaller and that will make it look better when you color a picture.

I like your picture, it looks great. :]