Process 1: the sketch
Making the sketch is one of the most important and difficult things. I have to improve a lot with it too, anyway, the sketch will decide how the drawing will be. I usually do like this, in layers:
a first sketching layer
a body Layer
a clothes Layer.
then, when everything is ok, i do the lineart.
Process 2: the lineart.
Usually i spend a lot of time doing this, but i...