Your starting out amazingly!
One thing I would say to focus on is the overall form of objects- for example, you can simplify the forms of the legs and arms into cylinders and then use that as a guideline for the anatomy.
You can watch some videos on the fundamentals of art, which are:
- Anatomy,
- Perspective
- Form and structure
- Lighting and shadow
If you search up "fundamentals of art beginners guide" on youtube you can get videos that explain it perfectly and give you exercises to do.
You're doing amazing! Keep practicing!
Your poses are really good. I think you could add some more life and energy to the poses by exaggerating the poses. For example, tilt the shoulders and hips more. The proportions are quite good but really exaggerating could bring lots of energy to your poses.
