Most of the specific criticism has been stated. I think you should, in general, practice more anatomy and get used to how each shape in a body works with eachother. What you can do is just, for now, draw from references as much as possible. Like every chance you get, just doodle what you see. Don't even worry about details, simply learn to get proportions down. I'm linking you to a thing that shows different poses every 30 seconds, and you're basically suppose to drawn each pose you see. It's really helpful

The site has a shit load of dynamic poses in general that will really help. You have a really interesting style though, and I look forward to seeing it develop (: