In my re-gripping experience, I have always found double-sided tape very helpful. Just bought a new pack today, matter of fact. I usually wrap some up the entire length of the handle to ensure proper adhesion, particularly when I am recycling a leather grip from elsewhere. The trickiest bit I find is the 1st wraparound and a half or so, as it inches upwards to the 2nd, I have a hard time preventing the leather from bubbling out as a result of either inadequate tautness or slippage.
WANTED: Avery M3 Control 95, Prince Precision Graphite 640PL (3/8)