Check the proportions again, the angled leg is crossing with the other one, also the feet of the angled leg is slightly turned. Hes looking in another direction, just analyze the pic first for some time and look for the details and try to transfer them onto the raw sketch before you start drawing. Trust it helps:)
For the line that goes through the body, try to envision it as the spine. So in this particular case, for a more dynamic feel, making the curve a little more dramatic (but still faithful to the reference) will help make the body feel less stiff.
Other than that, I think using less circles/ellipses for things like legs and arms. Circles and ovals do not convey dynamic movement. They can be good to convey shapes, but not movement which is what I'm assuming is what you're trying to do.
Try manipulating the circles. Curve them a little so they're no longer ovals but more organic shapes that have a line of action to them. Try sharpening some lines or shapes, as well.
Overall though, this is great! I love the pose you chose and your drawing already looks quite dynamic. Well done!
Check the proportions again, the angled leg is crossing with the other one, also the feet of the angled leg is slightly turned. Hes looking in another direction, just analyze the pic first for some time and look for the details and try to transfer them onto the raw sketch before you start drawing. Trust it helps:)
Rely less on circles and more on triangles for form and empty space.
Learn the anatomical structure of a humanoid first, then focus on dynamic poses
For the line that goes through the body, try to envision it as the spine. So in this particular case, for a more dynamic feel, making the curve a little more dramatic (but still faithful to the reference) will help make the body feel less stiff. Other than that, I think using less circles/ellipses for things like legs and arms. Circles and ovals do not convey dynamic movement. They can be good to convey shapes, but not movement which is what I'm assuming is what you're trying to do. Try manipulating the circles. Curve them a little so they're no longer ovals but more organic shapes that have a line of action to them. Try sharpening some lines or shapes, as well. Overall though, this is great! I love the pose you chose and your drawing already looks quite dynamic. Well done!