Genealogy does get harder as we venture before census era etc, so wills, poor law records, tax/poll registers can help in addition to parish registers. But one of the most vital things I find helpful is the names of the witnesses to marriages from 1754 onwards. You may find they were nothing more than regular witnesses (churchwarden, sexton etc) but as many of them are relatives of the bride and/or groom, they have certainly helped me along the way. I always trace the witnesses to marriages if one or both of the spouses is an elusive ancestor.