A few famous putting drills...

You have certainly heard the following drills :
“Double ball” drill, “weak-side” drill, “no-flex wrist” drill, “eyes closed” drill.
Here are what they consist in.

The double ball drill.

Objective : face perpendicular to target line when you hit the ball.

Set up two golf balls so that they are perpendicular to your target and on either side of the central line of the PaceYourPutt® mat (the central line will give you the path of the putter).
Practice hitting two balls at once towards your club — if your club face is square, the balls should hit the club at the same time and quite close together. If not, one will hit before the other, and you have more work to do.

The weak side drill.

Objective : keep the putter on track during swing

If you are right handed, try to putt a few balls with only your left arm (if you are left handed, putt the balls only with your right arm). You must be able to keep the putter on track during the backswing and follow through.
You will be able to feel how your lead shoulder does the whole stroke.
Repeat this exercise 10 times.
Then, place your right hand back in its normal position and putt; you will see how the left side (or right side for lefties) pulls the putter.

The no-flex wrist drill.

Objective : wrists do not flex.

You should not flex your wrists during the stroke: it would be a kiss of death.
If you notice that you flex your wrists during the stroke, here is a good drill for you.
Swing 2 putters at the same time with one in each hand (a couple inches apart). You must keep both clubs parallel and at the same distance during the entire backswing and follow-through.
If you flex one wrist, distance will be modified or clubs will hit each other.

The eyes closed drill.

Objective : reproduce same acceleration during follow-through.

Place 3 balls on the 10-foot line and putt towards the same target (hole or edge of mat) and keep your eyes open.
Putt 3 more balls but this time keep your eyes shut. The 3 balls should end up close to each other; it will mean you are able to reproduce the same backswing and follow through (or same acceleration).
Reproducing the same follow-through over and over again is important for consistent putting.

Image putting drill eyes closed