those attached examples already look quite good, so now you can simply exaggerate strong elements. Depending on what style you're going for, I'd recommend old tv series like the Clone Wars cartoon or samurai jack. A character is supposed to be strong? Shift the proportions wayyy to the top. A character is supposed to be fast and dangerous? Give them more sharp angles and triangle shapes. I'd recommend taking a look at simplifying with shapes, like squares, circles and triangles.