The afterlife as a world, not a backdrop
Bangsian fantasy fails when the afterlife is merely decorative — a strange setting that does not do narrative work. Building an afterlife that functions as a genuine world means thinking through its physical laws, its social organization, its relationship to time and memory, and the specific way it changes the people who inhabit it. Does time pass in the afterlife? Do the dead age, or remain at the moment of death? Can the dead meet figures from different centuries, and if so, what does that encounter cost both parties? The answers to these questions determine what kinds of stories are possible in your afterlife and what kinds of change your characters can undergo. An afterlife with genuine internal logic generates its conflicts organically; one without it requires the writer to impose conflicts from outside.