You can buy a good prepackaged heirloom storage kit, or you can make your own. After cleaning the quilt, take a photo to help you identify it later, then wrap it in acid-free tissue paper. Lay the folded, wrapped quilt in a flat storage box, along with a container of desiccant -- such as silica gel -- to absorb moisture. Close the box, and tape the photo to the lid. Then place it inside a plastic bag, which will guard against insects and moisture. This "archival" method of storing your quilt should keep it pristine for many years.