Choosing the right Golf Shaft
The best way to select the proper shaft is to base it on the distance you get when you hit your driver. For example if you struggle to carry the golfball 200 yards in the air then you would benefit from use a shaft shaft with a senior flex; If you hit your driver consistently shorter than that, then consider a ladies' shaft. Many golfers can carry it about 225 to 230 yards, and they should use regular shafts, while those big hitters who crush the golfball well past 250 yards should have clubs with stiff shafts. Extra-stiff shafts are reserved for those beasts who consistently pound their drives past the 300 yard mark.
Another critical component of choosing the right flex is the smoothness of your swing. A shaft with more flex works best for golfers with smooth swings, However herky-jerky swings should be fitted with a stiff shaft. Most male golfers attempt to overswing, this results in a jerkier swing motion, therefore they will be best suited with a regular or stiff flex shaft. If you are comfortable with the golf club doing most of the work, then a more flexible shaft may be better suited for you.
If you are uncomfortable choosing a golf shaft for yourself then have a professional club fitter assess your game. Since they are professionals, they will be able to assess the best shaft for you based on your distance and your swing mechanics. They will have you hit several shots to see if you hit the ball consistently to the left or right of your target, they will check your ball flight to see how high or low you hit your shots. They will also use a equipment to determine your clubhead and swing speeds.
Be sure to hit several golf balls using clubs with a variety of diferent shafts in order to see which shaft generates the best results for your game. How you feel when you hit the ball, should be the most important factor in determining the factor in choosing the best shaft for your game.
If a certain type of shaft causes you to hit the golf ball better than the others, then ignore the designation (Ladies, Seniors), and just use it.