Downswing

Start the downswing with the arms as opposed to the shoulders. Usually slicers will start the downswing by unwinding their shoulders, as a result they will be "hips square, shoulders open" on impact. This is not good! Most pros do it just the opposite. They start the downswing with their arms and lower body while keeping their shoulders square.

Try to get the clubhead to outrace your shoulders on the way down. Your chest should face the ball while your club whips through.