i think youre off to a great start! I agree the head is a bit big, but since youre drawing digitally, dont be afraid to just lasso around the head and size it down to fix your proportions! but you chose some difficult poses and I think you did rly well for a beginner! anatomy is difficult and im still learning how to improve mine. one thing i would suggest is to rent out some anatomy books so you can rly see how the body parts connect with each other. that way when youre building your figure from the stick figure, you know what shape represents what. this will be important too for your line details. keep it up! im still learning, but id be happy to redline any studies you do in the future!