Definitely dont think about where your head is - it should always be safely sitting between your ears, and if it isnt, you wont be worryinh about it any more
If you want to get more 'body lean' you need to think about where your 'inside' elbow is ... cos your body will follow it of course !
That is the first simple thing to feel for when you are riding anywhere - cos the most common prob is to keep the elbows almost locked into position ... I've even seen it with someones arse hanging off the bike :P
If you get your inside elbow lower everything else will follow much more naturally.