Along with using the dots on the fabric selvedge, when selecting fabrics for a quilt, I usually find my focus/primary fabric first. Then will pick subordinate colors I think work. I try to take the bolts and lay them out in proportion to how they will be viewed in the quilt. Most of the bolt of focus fabric; 1/2 of next primary fabric on top/below that; 1/3 of next fabric and so on. Sometimes I'll end up changing the focus fabric; sometimes some of the subordinate fabrics. But I find that layering the bolts with the approximate proportions exposed helps me see what does/does not work together.