Lots of good advice here, and now for my .02:
If your hips stay put, most other problems will fall away. If you don't sway (lateral movement), your hands (and club) should come right back to where they were. If you don't bob up and down (vertical movement), the clubhead will be
slightly below it's starting position at impact (I'm not sure why, but every video shows it to be true).
Your best friend will be a camcorder/mirror, and v1home/masking tape, respectively.
The tape goes on the mirror (use a friend) with a little cross showing your hips level and centered.