The greater the clubhead speed you generate, the more power your swing will have. There are many ways to increase clubhead speed, including physical strength and proper swing techniques. Physical strength will help you bring the club down and through the ball quicker, leading to much faster clubhead speeds. Weight training and physical activity will help build physical strength that will translate to a stronger golf swing.
Also, bringing the club back farther in the backswing will help give the club more time to generate speed when coming through the ball. It is, however, important to be controlled. Never overdo it. Keep control of your swing, or it will lead to hooks and slices.
Proper rotation and push of the hips through your swing will generate more power. When bringing the club through the ball, it is imperative to push your hips toward the target. This moves momentum through the ball and to the target. Rotating your hips develops torque in the swing and will lead to more power upon contact with the ball. Take time on the range to practice your hip rotation.
It is also important to have the proper equipment in order to develop a particular skill set as a golfer. A 15-handicap golfer would benefit from maximum forgiveness in a club, while a more skilled golfer would benefit greatly from clubs that rely on more accurate contact. It is important to be fitted professionally or to try clubs before buying them. Don't watch a pro golfer and expect to buy the same clubs and hit balls just like he does. Buying training equipment such as a weighted driver will help develop more power and strength in golfing muscles, which will translate to a more powerful swing.