I believe in reincarnation and summerland, but I also believe that people who can't forgive themselves for something they have done, they stay as spirits till they decide to forgive themselves for what they did, then they can reincarnate and move on, but there are also some spirits that don't get to move on and those are the ones that cause us harm and are negative, they can be nice too and not want to cause us harm.
I follow the wiccan Rede with mind, heart, & soul, to cause no harm, and to love unconditionally.