Master it…? No. Manage to do it…? Somewhat.
First time was unintentional, but it provided specific clues as how to pursue it further. I didn’t realize it at the time, but it happens in a half-sleep state. That teetering position between complete slumber and being awake.
During a normal sleep, my left arm was positioned to restrict blood flow, bringing about an episode of severe paresthesia, beyond the point of tingling, and becoming completely numb. It was so uncomfortable that I woke up crying. But I wasn’t crying out of pain or fear. I was crying out of complete sadness that my arm had gone numb. I sat up in bed, whimpering from pure despair. I could move my arm but could not feel a thing. Lifting my hand about a foot away from my face, I could clearly see a green aura dripping from my fingers. Not really dripping, but more like tentacles that were dangling from my fingertips. They were very long, dappling about my lap and all over the sheets.
My left arm was a black silhouette, and the green tentacles were gradient and glowing from my fingers. I held up my right arm, comparing the two, and could see detail of skin and structure, but the left arm was completely black, like a void. As I sat there whimpering, the tentacles slowly began retreating back into my fingertips. I could feel them infusing my left arm with life. After about twenty seconds, they had completely drawn back into my fingers, and upon that instant, I could see detail again in my arm. At that very moment, I could feel the tingling pain of paresthesia in my arm as it slumped at my side. I could no longer lift it and was completely awake at this point, wondering what the fuck had just happened.
This experience caused me to research more about the green stuff flowing out of my fingers. A Hindu priest told me that my spirit essence had slipped out of my physical body for a moment. He told me how to make it happen intentionally and I set upon a path to do it again. He gave me an exceptionally specific clue to know when it was taking place. He said to concentrate on that moment between sleep and being awake. Try to hover there for as long as possible. The body will become immobile but the conscious awareness remains alert. Listen for the sound of crackling, like rice crispies popping with milk, or a slow rumpling up of a potato chip bag.
It took at least two weeks of practice, learning to hover between sleep and awake. But finally, one night I was able to remain there for a moment, I really can’t say how long because what happened afterward captured my attention. I remember being there, teetering between the two realities. It seemed like a real place, but not a physical place. It’s like being in two places at once. Still aware of my physical surroundings, but also being somewhere else. Once I let it happen, just going with it, I really heard the sound of crackling, and yes, it’s just like rice crispies popping in a bowl of milk. Upon hearing that sound, I became motivated to sit up in bed, and I did just that. But to my surprise, my body was still lying down. My spirit sat up from the waist up, still attached at the physical legs. I looked over my shoulder and could see my physical torso to head body still sleeping in bed. But my spirit self was still attached to my legs. I freaked out and was immediately pulled back into my torso, my physical body completely awake.
I chickened out of jumping away from my body completely. It was very disturbing, but not really frightening. Very weird. I’ve never tried again, but since that time have heard numerous descriptions that include the crackling sound. Supposedly, that is the result of the essence peeling away from the physical realm. I’ve never tried again. I’m afraid I won’t be able to get back inside my body, but others have assured me there remains a sort of tethered chord between your essence and the body that pulls you back in when fear overcomes you. Apparently, fear is the enemy in that realm as well.
Since then, I’ve had other non physical experiences as well, actually very similar to @kevbo. But all were unintentional. I’ll probably try it again when I’m older and more settled in life. Now is not that time.