Hey Valerio, great job on these. Your structure and proportions are definitely getting there. The first thing I'd recommend is taking better photos of your artwork when sharing it. Even just studies. Us being in a visual medium, every aspect of the image presented will communicate something. In this photo, the uneven lighting makes certain parts of the image hard to read. Your photos in your other posts are perfectly fine. It also looks like you might be on rough newsprint. I'm not positive you are, but it's a lot easier getting clean lines if you have a smoother drawing surface. The next thing I'd recommend is drawing with more intention and energy. I can tell that you're drawing people, but if you take each individual parts of what you're drawing, it's really hard to tell what's going on. A possible solution is to start drawing with simpler lines. When I was in school, one of my teachers, @Erik Gist, told me that in quick sketch, especially at this stage in the drawing, you should only really be using C S I lines. That's C curves, S curves, and straights. I can tell you're sort of already doing it, but I think you're lacking in confidence in what you're drawing. Someone who does a really good job teaching that stuff is @Mike Mattesi. His book Force, and his videos are really good for injecting gesture into drawings. It's not necessarily about getting "pretty" drawings. It's all about getting the action and gesture of the pose. I've included a diagram of the Reilly Method, and some other demonstrations I did over other student drawings on how I might simplify drawings.

Hello! I would try and incorporate the whole body into a gesture drawing and find a few simple lines that describe the whole movement of the body. I think your lines describe the shapes of the body and the contour rather than the general gesture. Try using 2 or 3 lines max (l s or c) to describe the torso, legs and arms. Try and be bold and don't worry if it doesn't match the contour of the body. Proko has a great video on gesture. Maybe copy some of his drawings from that video and then use those ideas in your own drawings.