Q: i think its very effective in free kicks, penalty kicks and corner kicks..
A: to curve a soccer ball you have to hit the outside of the ball when you make contact with it. if you hit the left side of the ball the ball will curve from left to right and if you hit the right side of the ball it will curve from right to left. that is the basic way to curve a ball. the ball will also get more air if you shoot it with backspin. if you want the ball to dive down you have to hit it with topspin. also you can lean away from the ball when you strike it. it does something with you center of gravity and some people find that they strike the ball better this way. it is completely up to you. experiment on how you like kicking and work on your follow through. by practicing and by combining these skills you can effectively curve a ball on shots and free kicks. there are plenty of videos on you tube. i will provide a couple of the good ones for you. remember that you arent going to be able to curve the ball like the pros without a whole lot of practice. good luck. hope this helps you.