Recently I went back to using the line on my ball to align my putts. It's nothing set in stone in the sense that I won't always use the line, but it gives me a reference point and I still like to be intuitive with my putting. I found the line to be really good on short putts. Particularly the left-to-right short putt that I usually leave high. And I also learned that if the ball line 'feels' like it's aimed too far right, chances are my putter is aimed too far to the right. But if it feels like it's aimed too far left, then it's usually okay.
Anyway, Geoff Mangum had a post over at his forum at www.puttingzone.com on using the line on the ball to aim the putterface. His method is different and interesting and I'm going to try it out.
AIM THE BALL LINE
1. Aim from behind the ball,
2. walk to the marker on the green with the ball in hand,
3. squat low and look level at the target with the ball held at eye level so that the line on the ball is aimed directly at the target like a rifle,
4. lower the ball and the line vertically to the marker without changing the aim of the ball's line,
CHECK THE BALL LINE AIM FROM BEHIND
5. step back behind the ball to check the aim using your putter shaft to connect the dots of ball with line and target along the outside edge of the shaft to make sure the ball's line parallels the shaft edge,
AIM THE PUTTER FACE THRU THE BALL LINE
6. walk back to the ball and aim the putter face squarely thru the ball with the alignment mark on the putter matching the line on the ball and the sweetspot of the putter centered at the back of the line on the ball,
SET UP BESIDE THE BALL TO THE PUTTER FACE AS AIMED
7. set up to the putter face as aimed with the throat line the same as or parallel slightly behind the leading edge of the putter face and with the shoulder joints parallel to the aim of the putter face and with the eyeballs physically directly / vertically above the sweetspot of the putter,
8. aim the face itself (not the eyes) at the sweetspot of the putter face as if there is an arrow sticking straight thru the back of the head out of the bridge of your nose so that the arrow is perpendicular to the plane of your face (the same face plane as shown by holding flat palms behind each ear),
CHECK THE AIM OF THE BALL LINE AND PUTTER FACE FROM BESIDE THE BALL
9. close the left eye (eye closest to the target) and use the right eye to look inward at the point where your nose meets your eyebrow in a peak or arrow-head shape blocking your vision and note where on the ground about 1-2 feet left of the ball this visual border point appears to meet the ground,
10. make sure this peak point in your face / nose-eyebrow is positioned along the same line on the ground indicated by the line on the ball and the aim of the putter face,
11. rotate or swivel the head to turn the face and eyes towards the target so that the top of the head and top of the swivel axis simply spins in place and does not sway left or right as the face turns,
12. observe that the peak in your nose-eyebrow border appears to run in a straight line along the ground as a result of this head swivel and that this straight line is the same as the aim of the ball line and the putter face,
13. at the end of the distance, notice WHETHER the aim of the ball line and putter face point at the target as intended or to the left or to the right of the intended target spot by noticing what exact spot on the ground at the end of the line shows up just inside the peak, as this spot on the ground will be the same spot that the putter face and ball line actually aim at.
Depending upon the result of this final "checking" of where the ball line and putter face appear to aim (using the correct, accurate body procedure to find out), you will either agree that the putter face and ball line aim at the target as intended or see exactly which way and how much the aim is off and make the appropriate adjustment and check a second time. Once the checking verifies that the ball line has been aimed accurately, you can trust that a straight stroke thru the ball down the same aim the ball line indicates is exactly what you should do when you make the stroke.
Notice that unless in #7 above you position the eyeballs vertically above the ball (when the line on the ball is not tilted but is oriented vertically in plane to the ground), you will look down from slightly inside the ball on a tilted angle of view and the "line" on the ball will not actually appear straight, but will look more like a "rainbow" curve of a rope draped over the top of a beach ball seen on a slight tilted angle. The "line" on the ball will ONLY appear to be a straight line when the angle of view is straight down onto the line. So if the line is vertical, the angle of view also has to be vertical. If you position the eyeballs slightly inside the ball, the the line on the ball has to be tilted towards your face so that the line of sight aims straight down into the top of the line. otherwise, you will be looking at a curled "line" that biases your stroke to the inside with a pull stroke.
Here's a video on point #7 made by Geoff.
Points #9-#13 I'm still a little foggy on, but here's a video on it as well.