On curvy handles I get the thinest beavertail I can find. Wrap the bow above, thru the handel, and below with plastic wrap. Soak the beavertail in warm water. wrap it around the grip as tight as you can, using clamps on the back where I'm eventually going to stich it.
Let it dry, then do the process over some times 3 and 4 times. When I get it stretched as much as I think it will, I trim it to where it looks right, punch the holes and get it ready to install.