I specify that it is not the ultimate solution, just some tips as well as many others, for potential beginners.
If I can help even just one person, I'll be happy...

So from my experience from Discord, to keep it clear, I am not the know-it-all, far from it, just my desire to help with my poor knowledge....... Thank you... (always forced to justify myself, it's annoying)
So now it's clear, to begin, find a good rock quartz crystal, and program it with your third eye, put the intention in the stone.
After that, for few weeks, program your brain too for this intention. Repeat mentally everyday as often as you can: "I'm going to go outside of my body"
You must program your stone and your brain with great ambition, and without any doubt.
After these few weeks of daily brain programming, it's time to give a try.
Lay down in your bed, close your eyes with a good relaxing background music and without words. (for me it was a music in a loop: Brian Eno - An ending (Ascent))
Place the stone on your third eye, and let loose.
From my experience, after few minutes, I started to feel my body strongly vibrate. At this time, it is impressive but don't be afraid.
Focus on your intention while your body vibrate and repeat mentally I want to go outside of my body now, til it happen.
Sorry again for my approximate langage...
