Club face controls direction at take-offThe angle of the club face at impact determines the initial direction the ball travels, so keeping it square is the first priority.
Swing path determines curvatureWhether the ball curves left or right is largely dictated by your swing path — swinging too far outside-in or inside-out will create unwanted bend in the ball flight.
Set up square to get back to squareStarting your address position square to the target gives you the best chance of returning the club face correctly at impact, which is where it matters most.