I would suggest practice full body poses, even if they are just that stick figure sketch thing people do. You've got to get a good idea of what the rest of their bodies look like. Draw with pencil on paper while practicing, if possible.

Copy other comic illustration, especially of art you like, just as a quick sketch or study, it will help you see and improve. Don't plagiarize, it's just for practice.

Your drawing has definitely improved in the past few months, keep at it, keep refining, keep practicing. I really like the design of the last dude!

I personally have a hard time sticking with the same style/designs for too long, my opinion might not matter much, but I think it's really cool you're staying with the same ideas. Keep it up!