I wouldn’t recommend changing much on your carry firearm for your legal protection, however changing out a grip shouldn’t affect anything about the action of the firearm.
Have you ever altered a grip on any of your firearms for a better, more secure grip?
What special tools did you need? Any grip brands you prefer?
I haven’t changed my grip but have gotten instruction on changed where I applied pressure to the firearm. I was having trouble shooting compact pistols where I couldn’t get a full hand grip. Learned to not rely on my pinky
M&P 2.0’s come with different size palm swells. I swapped to the XL for a better fit. Does that count? 
We put a Pachmayr grip sleeve on my taurus pistol - it makes the grip fatter (which I like) and adds some rubbery-traction to the surface. Still don’t like shooting it much, but at least I feel like I have a secure grip on it.
We’ve added golf-club grip tape to some things because it improves traction without adding much bulk. I don’t like the look much, but it is pretty effective for making a grip less slippery.
I put a rubber Hogue slip on grip on 2nd gen Glock 22 .40SW & my Sig P228 better grip and slimmer fit, with pachmayr rubber grips swapped for factory plastic ones. Simple screw driver for the Sig
Looking at getting this for my Taurus, but don’t know if I will like it.
I used the adjustable palm swell thar came with my M&P. My hunting revolver came with very comfortable rubber type grips, so I’m good there. I have medium to large hands, but not overly huge, so I can usually grab most standard pistols, and be fine. As far as the traction, my hands are like sandpaper anyway, so even a damp, or sweaty grip doesn’t present much trouble for me.
I’ve put hockey tape on a shotgun before. Lol.
Niiiice 
My hubby does it, but I really have a hard time doing that… it’s kinda like writing in a book. Just goes against the grain in terms of “respecting your tools”… feels wrong to me 