>>114077058im not super great at it, but what i did to get to this level
(this is a couple months old and didnt get me anywhere so take this with a grain of salt)
> study animationknowledge of how things flow in motion is invaluable for doing good motion in a single picture. most institutions bundle comics and illustration together, but animation is honestly just as (if not more) important
look at frame-by-frames of your favorite motions you see in movies and animations and learn to break down how its done. the weight, motion, and follow through are important
> focus on exaggerationexaggerate perspective, line weights, and the motions. keeping things flat is boring, so make use of the camera and have things coming at you. use line weights to exaggerate depth and emphasis. exaggerate the motions to add some more punch to it
> line-of-action and compositionstill learning and improving on this one myself, but where you place characters and how their line of action flows around the frame is important. especially in a comic page where it can be used to pull the reader's eyes to areas you want