Way to go, on your first attempts here, Baobeir.
Say, I feel that these lines are a little bit to faint. Would you please work with a darker pencil of graphite, like a 2B, for example, while loosening up with 30 minutes of 30 second scribble poses? (60 of 'em)
The reason why you should do this is because, it could make the perception of the edges more clearer, and less ambiguous.
My hat's off to you, and I hope you've found this extremely and positively concrete and beneficial.
Fantastic work!! I especially love the lying down one! The twist in the hips is captured so well. Your lines seem to becoming confident - this is awesome, keep it up! Some of the best advice I ever received was to draw smart with my lines - in other words, think a bit about the line before you put it down. This makes lines much more confident and they serve their purpose better! You're totally getting this! Another helpful tip I recieved from a life drawing teacher was to think about the rib cage, spine, and pelvis. At first I refused because I just wanted to draw contours, but I ended up learning a lot from doing an oval for the rib cage, a line of action for the spine, and another oval for the pelvis. It seriously helps you think a different way, and I think this could help you too! Fantastic work, keep it up!