And still one more (you should be able to tell that this has always been a problem for me; I've listened to every witchdoctor out there!)
I used to compensate for the slice by just aiming more to the left of the fairway. Makes sense right - fix a banana ball right by aiming more to the left?
The problem I had was that I started the swing out of alignment- Standing at the tee box and aiming left, I had a habit of having my shoulders aiming aligned to left (open), and when I went through my swing I was even more open than before, and really was OTT. The morale of the story is make sure your shoulders are aligned right