There are so many ways you can hold the putter, Mark goes through his top three for consistent putting. The first grip Mark Crossfield showcases is the standard old school putting grip. It is the standard grip with your left hand above right, the palm of your hand rather than in your fingers like a normal golf grip.
The second grip is the prayer grip where you have both hands either side of the shaft and the fingers pointing down the shaft. The final grip is the one Jordan Spieth is currently using in the reverse grip, where you have you hands the other way round to the norm. This has a few different benefits is that it can reduce wrist hinge and help rotate through impact.
Which grip do you use? Have you tried any of these before?