Once your shoulders are working properly, swing level as though you are moving the club along a table. This will ensure an uncomplicated face rotation, avoiding hooks and slices.
Your swing arc should be smooth and continuous. At no point should you interrupt the momentum in order to re-route. Momentum helps your body work more efficiently.
Foot action cannot be overstated. This is where your power comes from. The more you can sequence this out in your swing, the more consistent and balanced you will be.