Most of the people image it simply: paradise, purgatory, hell. I can compare it with a house: 5 floors - up, 0 floor, 5 floors - down. In the Bible: Jesus Christ said: In the house of my father there are many monasteries (Gospel of John, v.14:2).
Curiously, the ancient egiptians had a god, called Tot, essence with a body like human and a head of jackal. The same essences are in "-1 world". They saw them.
There may be some variants. Saints do not need a reincarnation. Habitants of other upper worlds may reicarnate. From the hell - never. From other downworlds may go up, if somebody will pray for him. Till the Judgment