All great players can curve the ball, maybe to shape a shot into a tucked pin, or play around a tree. Some pre-set their body and clubface alignment at address; others manipulate the face during the swing.
Jack Nicklaus, for example, when trying to hit a fade, will set up with his feet and body open (aligned well left of his target) and his clubface aimed at the target. Then he simply swings along his body lines so the face is slightly open to his path at impact, resulting in a left-to-right ball flight. He makes the opposite adjustments for a draw.
Bubba Watson, on the other hand, purposely holds the face open through impact for a fade or rolls his arms over for a draw.
Jack's pre-setting technique might be easier for the average golfer, if you don't subconsciously adjust the face alignment during the swing. That can cause a "double-cross" (aiming left and hitting a pull hook).
But I like Bubba's in-swing method. It increases sensitivity for the clubface so you can control the amount of sidespin. Clubface awareness also helps you develop your short game.
Try this on the range: Place clubs in front of and behind the ball, on your target line, and insert a shaft or umbrella vertically 10 yards in front (above). That gives you a precise image of your target and the starting line of your shots. Then, practice fades by aiming left, clearing your hips earlier on the downswing, swinging to the left and holding the face open with your forearms. Practice draws by aiming right, slowing your hip turn through impact, swinging to the right and closing the face by rotating your right forearm over your left.
Jim Flick, a longtime Golf Digest Teaching Professional and PGA Golf Professional Hall of Famer, worked with hundreds of amateurs and tour players including Jack Nicklaus.