I try to train myself and my students to have some awareness of an imaginary plane that is approximately 60 deg for irons and wedges, and 45 degrees for the woods! From the takeaway training to have the shaft move away from the ball backward upwards and inwards 60deg while maintaining the radius of the swing, until the club is parallel to the ground on the backswing , help eliminate many common errors we see in the golf swing. As the right arm folds more the club will go more vertical and off that plane, which you should try to return to on the downswing !