I really like these. The first thing I would do is try drawing in the form first, they feel very outliny. Also, I would practice gesture more, they feel very stiff. Lastly, I would just be careful on the head sizes. Hopefully this helps!
I really like these, I would try learning the anatomy the best you can. In the 30 minute one the head is a little to small, so fixing that little thing can definitely make the drawing ten times stronger. I also really like the 1 minute ones. Just be careful not to outline them. I used to make that problem all the time, but it can make a huge difference as well.
