I had the same problem (and still hook 'm frequently) and it really took a looong time to find the problem. So whenever I start hitting hooks this is what I pay attention to (this works for me, don't know if it will help you).
- grip, obviously
- hands, arms, entire body relaxed
- keep head still and keep looking at the ball in my backswing
- keep backswing compact and hold my right elbow as close to my body as possible (in a natural way)
- and finally, for me this was really hard to learn, start the downswing from the ground up. If my hands go first I always produce real bad hooks.
As you may have noticed I'm high handicapper and still have soo much to learn.
Maybe my list is complete nonsense, but somehow it works for me.
Hope this helps. Good luck with the swing