Wow, this is a long thread. I have some thoughts I'd like to share based on the original post but since I haven't read more than 4-5 pages, I apologize right now if this is redundant. Moderators, feel free to delete this post if it is - I won't be hurt.
Focussing on the ringing in my ears is actually the very first technique I used (I've probably tried them all over the years) that produced real results that forced me to change my mind from not really beliving in AP but being curious to beliving this stuff really happens to people. What happened was that eventually (it was probably somewhere between 1-2 hours of laying in bed focussing on the ringing) the ringing just kind of
became the exit vibrations. And holy cow! They were serious vibrations. Not the kind of subtle waves you feel when doing energy/body awareness type excercises. It literally felt like a bucket of ice water was dumped over my body starting at my head and moving down to my feet. Shocked me so much I forced myself to wake up (and then regretted doing that considering this was what I was trying to accomplish).
But the thing I wanted to add relates to the focussing on the blackness behind the eyes. This has never worked for me - it just keeps me awake, which kinda' makes sense because by doing this, you are deliberatley keeping at least a part of your body awake. I tried doing this when I used this ear-ringing method, along with trying like heck to silence my mind of all thoughts, and nothing ever happened. When it finally worked, I had given up on staring into my eyelids and keeping my mind silent, and instead, kept focussing on the ringing, which got progressively louder, while just letting my mind wander like it naturally does when I go to sleep at night.
My personal opinion is that this technique could be really good for you but if it's not working, try forgetting about using your physical eyes to stare into the darkness while trying to AP. Either let your mind wander on it's own (tricky though, could make you just fall alseep like usual) or imagine something in your mind's eye and concentrate on that. In other words, you've got to go from physical sight to mind's eye sight (not sure how else to describe it). At least, I do. You can even just imagine looking into blackness in your mind as if you were staring at your closed eyelids with your physical eyes, but you've got to eventually make that subtle shift from seeing blackness with your physical eyes to seeing blackness in your mind (whatever "mind" is

).