Jinny Beyer has a book in which she discusses her use of color and strongly recommends including a very dark fabric that looks like a solid at a distance. I think a lot of quilts "perk up" when you follow this advice - brights look brighter and more interesting with a good dark in the mix. Here is one fabric that fits that description:
If you want to ease into solids, try using some fabrics that read as solids with your other fabrics.