You can simply put one side over one of another color and sew them together. Or are you putting them into squares, maybe sewed on a backing? You could simply sew them all together like any other block, or put a plain color band between them for contrast. Crazy quilt means anything goes. Do it so that you like it, that's what makes it so much fun. Mix and match, or make them all the same color/tone/shade. Have fun with this piece of art.