Track the ball as if you were going to catch it. Keep the non-playing hand on the throat of the racquet to prevent it from going back too early.
When the ball touches your strings you should focus on the feel of brushing it up and across. Let the racquet do the work for you. Don't force it.
On groundstrokes, always finish with the butt of the racquet pointing to where you hit the ball. Minimize your backswing - the finish is more important.