hand Study ..
These gestures look great, nice job including the wrist. I agree with Radoslav, the shading is your easiest zone for improvement. When using tone "paper", try to limit your use of white to only the brightest highlights. 90% of the shading should come from your paper value and pencil, the last 10% is the white, aka the topping on the cake. (obviously not a hard and fast rule, but a good place to start)
The line work its nice and gestural, but when you begin to shade it gets weird. Try to shade with more soft gestural strokes following the form, you kind a have it. GL.