I rarely do a controlled scrappy. My favorite scrappies are random. The secret to making anything work together is separating lights and darks. The more contrast the prettier the quilt. I, personally don't worry about the prints themselves. The only thing I watch is that I don't add any gold etched fabrics. I just don't like the look. Reminds me of wearing tennis shoes with an evening gown! LOL. But other than that, I use whatever comes out of my scrap bin. I mix fruit fabrics, dots, stripes, florals, and even fabric with words. I don't care if they are pastel or bright as long as there is a mix of both throughout the quilt. My only 'rule' to myself is that I need to use an almost equal amount of lights and darks and lots of mediums, and the more colors the better.