Trance denotes any state of awareness or consciousness other than normal waking consciousness. Trance states may occur involuntarily and unbidden.
The term trance may be associated with hypnosis, meditation, magic,flow, and prayer. It may also be related to the earlier generic term, altered state of consiousness, which is no longer used in "consiousness studies" discourse.
sit comfortabely and meditate for a while.When you are completely relaxed.Now visualize that you are climbing down a ladder in the dark .On the exhale feel yourself climbing a step or two down the ladder.On the inhale,feel yourself holding still on the ladder.Now feel like you are falling down the ladder (let go off ladder and free fall backward).If u feel sleepy just focus on your body.
This is simplest method to induce Trance.
Note:- Trance can be induced by self-hypnosis too but it involves lot of risk.