To me the most important thing in composition is disparity. Thus black and white are the strong colors, with a spot of red to mark the other corner of a triangle which is by no means equilateral, isosceles, or right. To vary this still further use yellow, then, later, blue. Anything suggestive of symmetry is decidedly undesirable, except possibly where an approximate symmetry is used in a detail to enhance the inequality with the general scheme.