Your stuff is looking good. 3 of the most important things in regards to figure drawing are:
1) Anatomy - Study anatomy and how the muscles attach to the bones and what muscles are important in representing the figure. Start with the Skeleton and then work your way from there with different muscle groups. You already seem to have a good grasp on gesture and contrapposto.
2) Practice - Try to practice as much as possible getting the anatomy/proportions accurate. Your proportions look fairly convincing but your anatomy needs more practice.
3) Thought - Probably the most important part of figure drawing and drawing in general. Instead of just rushing into a drawing, stare at it. Try to figure out the way you are going to approach this drawing giving the amount of time you have (how long were these poses by the way?). Figure out what you are trying to express through your techniques. For example, do I want a super accurate representation, do I want to emphasize light/shadow, do I want to express the figure through contour line, etc.. This will get easier with more practice and a better knowledge of anatomy. Also, think before you put a mark down. If this mark serves no purpose then don't waste your time making it.
All three of these go hand in hand and you should be constantly thinking while drawing the figure. Once you stop thinking you are no longer providing a humanistic expression of the figure.
Hope this helps! Keep up the good work.
Think with your head not with your heart.