Mark Erickson once told me, while I was studying painting, that to reach an harmony of color in any painting, one should divide the canvas in 4 and see if the colors are repeated (up left corner-down right corner / up right corner – down left corner).
It really works out. And now I see there’s some green and blue missing in the down right corner of the canvas. Or, I should cover some blue. But I kind of like it this way.