Dream logic and its internal consistency
Surrealism is not randomness wearing a literary hat. Dream sequences follow their own emotional logic — cause and effect operate, but according to psychological rather than physical laws. A man becomes a telephone because he has been trying to reach someone who will not answer. A staircase descends endlessly because the character cannot stop grieving. Every surrealist image and event should feel inevitable in retrospect, the way a dream does when you wake from it. Build the grammar of your surrealist world and apply it consistently. Readers tolerate a great deal of strangeness if they can sense the underlying emotional coherence.