Back in the day, when I was hitting my nose, I realized that I was unconsciously using a too-closed stance, and actually pivoting away from the target to an extent. I had gotten so used to stressing a "perfect" prepositioned stance, that I had let it go too far.
I have completely relaxed my stance since then, and opened it up. The way I retrained myself to start by just facing the target straight on, then turn my feet, but not so much that I have to reposition, or "turn" my head back toward target. It seems contradictory, but often your feet will still be properly positioned - if not just slightly open - and gravity won't be pulling your face into the path of the string. Secondary anchors also help - fletching to nose, for instance.