Good question, this thread is very relevant to me right now. Thanks for asking it.
I have trouble with concentrating on the breath. I can hardly feel it at all. I commit the biggest mistake by roving all over from nostril, chest, abdomen and back again. I just can't seem to feel my breath after a while.
Also, someone said something about sensation/awareness. What I want to do is focus on emptiness, just being aware, just being. No breath focus, just keeping mindfullness of the holistic you and the holistic situation. I'm not sure if this is the way to go because the Buddah taught about using the breath. I don't want to reinvent the wheel to coin a phrase.
Awareness of awareness is just being aware of everything and anything. Thie thing is - when sensations arise, an itch, a pain etc, I don't acknowledge them with 'itch, itch,' or 'thinking, thinking', or similar, I ignore them. I just find it a contradiction to use the 'mind' to focus on the breath, in order to not use the mind.