With really clean surfaces or maybe a bit of grip glue (done them both ways, I've used compressed air to "blow" the grips on, after blowing the old ones off. I'm sure many here have done the same. Using an air gun and aiming the flow at the flange end of the grip will blow compressed air inside the grip, expanding it to slide off or on.
I've used grip glue and also hair spray (back in the '80s). More often than not, I've not used anything, with clean grips and bars/throttle tube, the grips will grip very well. Apparently Motorcyclist online's Ari Henning also tends to avoid glues and pointed out some glues may damage the grip, if not a specific grip glue. Click here
I also speak with a bit of experience. Having worked in motorcycle sales, accessories/parts in a small mid size dealership I've probably installed literally hundreds of grips, especially the foam Grab On grips and similar ones. Often the grips were changed out on new bikes or near new. I'd blow off the old grips, without damaging them, then blow on the new grips.
Some off road style grips, not sure about some street grips, have circumfrential grooves in them for safety wire. The grips are acutally safety wired on, with the small clipped tip stuck into the grip when done. Never done it, but clearly the actual winding of the wire need be done with some care to avoid "cheese slicing" the grip and ruining it. One of the reasons I haven't done it before.