The picture to the right provides the answer.  Note where the red lines intersect.  In other words, divide the image via two equidistant horizontal and two equidistant vertical lines. Place the "action" along the dividing lines, and especially at the intersections.  Simple, yet effective. 

Well, not really a mistake, but there are better ways to compose a picture.  Let's consider the beach picture on the left.   Look at the picture's main elements.  The beach chairs & parasol, the goal, the dividing line between beach and water / sky. 

What seems to be the principle here?

(c) Christian Wagner, 2001.