Strategies

aphorisms, poetry, and etc.
semi-artistic efforts to crystallize some particular description or aspect of the mystical experience in words
God is Love (Christian and Sufi in particular)meaning a spirit force, Atman is Brahman (Advaitan), Zen haiku, Rumi's love poems (Sufism). Over time many of these have become trite slogans, losing their core meaning as depictions of practical experience, i.e. "God is Love"—describing the power of creation inherent in pure desire/unconflicted singlemindedness of will.
koans, riddles, and metaphysical contradictions
irresolvable tasks or lines of thought designed to direct one away from intellectualism and effort towards direct experience.
The classic "What is the sound of one hand?" (Zen) (or the more popular variant, "What is the sound of one hand clapping?") or "How many angels can stand on the head of a pin?" (Christian). Sometimes these are dismissed as mere incomprehensible silliness (see humor, below); sometimes they are taken as serious questions whose answers would have mystical significance. In either case, the intention is lost; the point being that excessive effort in contemplating the impossible leads the initiate to give up the ego pursuit of doing/getting as opposed to the unity experience of being/having.
The evocative Taoist phrase—To yield is to be preserved whole, to be bent is to become straight, to be empty is to be full, to have little is to possess—is another example of a metaphysical contradiction describing the path of emptying of the learned self.
humor and humorous stories
teachings that simultaneously draw one away from serious discussion and highlight metaphysical points
Primary examples are the Nasrudin tales, many of which focus on the unreliability of perception, e.g. someone shouts at Nasrudin sitting on a river bank, "How do I get across?" "You are across." he replies; Bektashi jokes, which serve as a means of opposing the pressures put on society by Orthodox Islam, and the Trickster or Animal Spirit stories passed down in Native American, Australian Aboriginal, and African Tribal folklore. Even the familiar "Br'er Rabbit and the Tar Baby", for example, is fairly acute psychology wrapped in a children's tale. Humor of this sort is often corrupted into mere jokes: some Nasrudin tales have a clear metaphysics built in, while others have devolved into little more than depictions of a crazy, dimwitted old man.
parables and metaphor
stories designed to teach a particular but unconventional metaphysical view of reality indirectly, by using analogy
One familiar example—the Garden of Eden story of Adam and Eve being cast out in shame—has lost its metaphorical meaning over time; the psychological/metaphysical consequences of shame when the innocent creative ego (feminine aspect) is tempted to reach for power and subsequently enters the belief in duality (eating of the tree of good and evil) because reason (masculine aspect of mind) has yet to waken. In the story, return to the Garden and Tree of Eternal Aliveness (divine reality) is only possible through purification of mind (the gate is protected by the lone innocent cherubim/Self wielding a flaming sword.) Compare this to the symbols of fire, masculine/feminine unity, time, fearlessness, and ego transcendence found in images of "Shiva the Destroyer" (Hindu) where the transformational process is described by visual metaphors. Christ is well-known for his use of parables, consistently using them to teach compassion and inclusion, while many contain hidden metaphorical content for "those who have ears to hear." In one of the most enigmatic stories from the Gospel of Thomas, he describes the Kingdom of Heaven as like an old woman returning home after a long journey, carrying all she values—a bag full of grain—on her back. A tear allows the grain to escape during the journey and she arrives home to discover it empty. Very Buddhist in tone, each word of the story has significance in describing the return path to the divine through a gradual emptying of earthbound value concepts and subtle internal conflicts. The use of the term, old woman, is a common metaphor related to the mind's incapacity to create, when controlled by embedded defensive ego values.
These categories are, of course, intended only as guidelines; many mystical teachings cover the gamut. For instance, Yunus Emre's famous passage:
I climbed into the plum tree
and ate the grapes I found there.
The owner of the garden called to me,
"Why are you eating my walnuts?"
is humor, parable, poem, and koan all at once as it describes the human potential for timelessness and moving beyond the vagaries of perception and levels.