Basic rules I was taught 1/3 and 2/3 for coulor mix, avoid straight lines, the human eye tends to look for straight lines and distintive shaped blobs of one colour, that gives a good aiming mark. Some insist the colours should Feather into one another. Easy enough with yard broom, emergency painting tool Mk 1. :-D
Could try this if feel adventourus. http://cdn.damninteresting.com/wp-content/uploads/2005/11/dazzle1.jpg