When setting out on your first steps to develop you skills at figure drawing, I recommend documenting your progression in a sketch book. Any size will do, A4, A3 or square. Use it to chart your development. Your first sketches are important to document even if you are not happy with them or even embarrassed by them, they will help to show how far you have progressed every time you make a new breakthrough.
Try to capture the energy and flow of action. Keep the sketches loose and light to start with. Try to feel the action as you put it down on paper
Experiment with different shapes and sizes
Here are some more links to earlier posts on figure drawing
Also check out David finch drawing heads
David Finch's channel