Critique Me pls - 2 days of practice

View my drawings here:https://imgur.com/gallery/day-1-2-practice-MepmlkZ

hello, i have some experience but i want feedback please.
these are some sketches done in 
30 secs, 1 min, 5 min, and 10 min

all done in pen and brush pen.

how can i further improve?

That's a really good start! So, generally gesture drawings focus on form and movement. Your figures have a good general structure, but what you want to do is focus on the larger shape at hand. Try to start with a single line indicating movement, then block out the remaining figure, in shapes that lean more geometric than curves. From there on, you can focus on the details and the contours of the body, including shadows. When you break things down into large blocks, the shadows tend to become apparent and neat.