The stroke, and the routine that comes before it.

A routine you repeat every time

Dr. Dave Alciatore's site says a pre-shot routine has to be consistent, purposeful and disciplined. His recommended order:

1. Visualize the shot and the cue ball's path while standing.
2. Chalk. Hold the cue tip angled down and swipe the chalk across the tip's edges while rotating the cue, then check that it is fully covered. Do not grind or twist the chalk on the tip.
3. Aim and align while you are still standing.
4. Lock in your vision center and drop straight down into the stance.
5. Once down, focus only on the stroke. Make no new decisions.

Take the same number of practice strokes at the same tempo every time, then pause at the set position to recheck aim and tip placement. Only make fine adjustments once you are down. If the shot suddenly looks very different, stand up and start the routine over rather than abandoning the picture you set while standing.

His stroke checklist condenses it into ten steps: stance, set and aim, warm-up strokes, pause and set, pull back smoothly, pause at the end of the backswing, accelerate forward, gaze at the object ball, follow through, freeze.

Pendulum or piston?

In a pendulum stroke the upper arm stays still and only the forearm swings from the elbow. With a pure pendulum, the tip comes back to the aimed spot on the cue ball and travels nearly straight through contact.

In a piston stroke the elbow and shoulder work together so the tip moves in a straight line the whole way. Many snooker players use it, guiding the cue along the chest and chin.

The elbow drop question

Most professionals drop the elbow after the cue ball has been struck, especially on firmer shots, which puts the hand on a "J" shaped path. Some do it on purpose; for others it is just the arm's momentum. Bob Jewett, quoted on Dr. Dave's site, observed it on power shots by Allison Fisher and Nick Varner.

Dropping the elbow before contact is the problem. It makes the tip hit higher than intended and can bring a "chicken wing" with it. Dr. Dave's site says most players, beginners especially, are more accurate without it, though a small drop or one that happens after contact is fine. Drills to remove it include air strokes beside the cue ball, balancing a chalk cube on the elbow, and stroking with the shoulder and elbow against a wall.

Back slowly, pause, accelerate

• Pull back slowly and change direction without a jerk. A rushed transition causes body movement and errors.
• Pause. A pause at the set position gives your eyes time to confirm aim and tip placement; a pause at the end of the backswing helps stop a rushed transition. Mike Page warns that a backswing pause can hide the real problem of bringing the cue back too fast.
• Accelerate through the ball. Decelerating into the cue ball hurts timing and speed control.
• Keep the cue level. Raise the butt only enough to clear the rail; an elevated cue makes off-center hits curve.

What follow-through does and does not do

Because the tip touches the ball for only about a thousandth of a second, follow-through cannot add power, spin or accuracy by itself. It is evidence of what the stroke was doing before contact. Two shots with the same cue speed, contact point and aim line produce the same result however different their follow-throughs look. That said, a very short follow-through often means a tense or decelerating stroke, and deliberately cutting it off tends to reduce cue speed at impact. After the shot, stay down and still, like a relaxed statue, and do not lift your head to watch the ball.

For a sense of scale: the cue weighs about three times as much as the cue ball, and a center-ball hit sends the cue ball off roughly 30 to 40 percent faster than the cue was moving.

Where to look last

Most top players look at the object ball last. Dr. Dave lists advantages (holding the shot picture, a straighter delivery, a stiller head, less urge to "hit" the cue ball) but calls them slight. Some great players look at the cue ball last, including snooker's Stephen Hendry. A still head and a focused final stroke matter more than which ball you watch.

A suggested object-ball-last sequence: look at the object ball as you get down, check tip position and aim with the cue still, watch the cue ball during warm-up strokes, recheck, then fix your eyes on the object ball for the final stroke. Looking at the cue ball last can suit jump and massé shots, finesse safeties, kick shots where spin matters, and power breaks.

Dr. Dave's own view is that no single stroke suits everyone: an accurate, consistent stroke is a good stroke even if it breaks some of these guidelines.