My ex was heavily into this. All I can say is that I don't recommend it. As Russell pointed out, it's dangerous. I mean, go parachuting or bungy jumping instead. Just for safety

Best advice I can give is stay sober and never do this while tipsy. It's not much of an advice but I was never comfortable about it. I just indulged her.

I thought it was best to use one hand and press on the each side of the adam's apple without pressing the adam's apple itself. The reason I did this is because there's a muscle there which relaxes when she's about to pass out. She's a nurse and told me what to do, so I was pretty confident it would be all right.

Why one hand? Because I could support myself with the other while fucking her lying down She liked to be suffocated while she came. Which added another element of danger, because she could hardly give me any feedback in that state. But her orgasms where utterly insane. She was having spasms for minutes. So there must be something in it.

edit: Yes, she's still alive. She's my ex for another reason.