Technique to induce vibrations?

OK so I am new here, but I am not inexperienced with AP. While I have never exited my body, I have known about this phenomenon for about 4 years now. Last year I tried to project and achieved vibrations on 3 separate occasions, one of which I heard a popping sound inside my neck. Anyways, each time i got so scared that I chickened out from moving. I can't remember exactly how I got to vibrations, but I think this was one helpful way of doing it:

When your body is really relaxed during your attempt (body asleep), cross your physical eyes and look up into your forehead. You should hear a sort of dark, pulsating vibration sound inside your skull and if done correctly, it will cause your spine to tingle slightly. Oftentimes, when my body is asleep, this is all i need to "jump start" the vibrations. You can even try it now if you are fully conscious, and you will hear the same sound/ get the same sensation. Hope it helps.

Anyone else use any specific method to induce vibrations? I have never exited into OBE but have experienced full vibrations. I have no doubt that I was close.