Spin basics: To make your shot check up, swing on a steeper path, and keep your hands and wrists firm through impact.
Spin is a tricky thing. When you're trying to avoid it -- say, on a tee shot, where sidespin puts you in the trees -- it's easy to make it happen. But what about on a short-iron or wedge shot, when you want the ball to check and stop? The good kind of spin -- backspin -- comes from hitting the ball cleanly, then making a divot after impact. The biggest mistake is trying to pinch down on the ball and ripping out a big divot, often hitting the ground before the ball. You'll dig up some turf, but you won't create much backspin.
To really put stop on it, take one less club, so you're making a more aggressive swing. With a steep angle of attack, hit the ball while keeping your hands and wrists firm. Your divot should be a shallow scrape pointing straight at the target -- not a worker's trench.
Your impulse might be to play the ball back. Don't. Play it an inch in front of center with a short iron so you can hit it higher. A high shot will come in more vertically and roll out less, enhancing the effect of the backspin.
Where you need spin:
No. 17 / TPC Sawgrass
It's only 137 yards, but if the flagstick is back-right, you've got to get it to hit and stop.
Where you don't:
No. 9 / Augusta National
The pin is always near the edge of the big shelf up top. Spin it too much, and you'll end up back in the crosswalk.