Fighting

Fighting: A show of Force.

Punching

BAD PUNCH: It's not horrible, it just lacks a certain force. Even though the form is good on both characters there's something that needs to be done to show this punch packed a wallop.	GOOD PUNCH: This is MUCH better. The force of the punch is shown in the shape of an arrow. The horizontal line coming from the attacker and the lines of the targets body bending at the point of impact. Making the fist a "blur" of lines helps give a sense of speed and power to the punch.
Kicking

BAD KICK: Same deal here. with the target being stick as a board it tells us this kick was nothing special. the attacker appears to be merely raising her foot at the target	GOOD KICK: Now THAT had to hurt! Again..the horizontal line of force crumples the targets body around the point of impact. He probably won't be getting up for a while. Also the attacker's body is much more a part of this kick. all the balance is thrown into it giving the impression of a mighty delivery.
Adding details:
	When you get to the stage of cleaning up your work and adding in details be sure and incorporate lines that translate the action taking place. The edges of her fist and arms are quick strokes following the direction her arm is travelling. his head is knocked back from the point of impact. His hair and spit show the continuance of the force of the punch. I put curved lines on his check to show an indentation where her fist connected.