)
Just keep drawing. Draw, draw, draw, and then draw some more.
Like, even with one drawing. A lot of times setting something aside and then reworking it a few days later will really help it come together. Then a month later rework it some more. Always have some drawings that you are working on, and when those are how you'd like them, draw some more.
I wrote some more about [reworking sketches until they're where you want them to be here](/forums/art/topics/artists-group-chat?post_id=4745489#post_4745489), with some examples.
I find it helps to look at my hero's sketchbooks, too. Seeing them floundering and struggling with a pose helps me not give up when I'm having trouble getting something the way I want it.