There are many components involved. A spinner has to spend a lot of time in the nets. You can possibly become a spinner by participating in a practice session for a couple of hours. But you cannot become a real good spinner. A spinner must first understand what exactly is spinning the ball. A real spinner should possess the following qualities, otherwise he can only be termed a roller.
The number one thing is to have revolutions on the ball. Then you overspin your off- or legbreaks. There are two types when it comes to imparting spin: overspin and sidespin. A ball that is sidespun is mostly delivered with an improper action and is against the fundamentals of spin bowling. A real spinner will overspin his off- or legbreak, which, when it hits the ground, will have bounce, a lot of drift and turn. A sidespun delivery will only break – it will take a deviation. An overspun delivery will spin, bounce and then turn in or away sharply.
Then we come to control. The spinner needs to have control over the flight, the parabola. Flight does not mean just throwing the ball in the air. Flight means you spin the ball in such a way that you impart revolutions to the ball with the idea of breaking the ball to exhibit the parabola or dip. By doing that you put the batsman in two minds – whether he should come forward or stay back. But if the flight does not land properly, it can end up in a full toss.
The concept of a good spinner also includes bowling from over the wicket to both the right- and left-handed batsman. The present trend is for spinners to come round the wicket, which is negative and indicates you do not want to get punished. A spin bowler will have to give runs to get a wicket, but he should not gift it.
A spinner is not complete without mastering line and length. He must utilise the field to make the batsman play such strokes that will end up in a catch. That depends on the line he is bowling, his ability to flight the ball, to make the batsman come forward, or spin the ball to such an extent that the batsman probably tries to cut, pull, drive or edge. That is the culmination of a spinner planning and executing the downfall of a good batsman. For all this to happen, all the above fundamentals are compulsory. Turn, flight and parabola separate a genuine spinner from an ordinary spinner.