When photographing action, or activity, look for the "Peak" moment.  That is the point at which the action reaches it's apex. In Basketball, that may be the moment a defender has his arm fully extended, as in the example here, in tennis it might be the moment a player lunges for a volley, in baseball, it may be  the instant before the pitcher releases the ball at the end  of his wind up.  The moment is different in each case, but the principle is the same.  By training your eye to see these peak moments, you will produce more and more winning pictures.