I usually simply don't (aging off). If I am not ready for them to die, they are not allowed. Plus I keep a number of saved versions of my favorites in my library to play with again.
However, if I am detached and ready for their story to finish, I wouldn't mind some prep. Perhaps build a crypt and invite friends and family over to say goodbye one last time. Then it is just deciding if I want to see the ghost, but if it is my fav I probably do.