I also use 3M industrial grip tape on places such as the front of the old A2 pistol grip before I swapped it out for the MAGPUL pistol grip, wrapped the magwell from the front around to the R/H side, and on the face of the modded switch on my carbines TLR-1.

Rubbing the grip tape with a large 3/8 th drive socket helps it adhere to the surface it's being applied to, and knocks down the excessively rough texture of the tape while keeping a texture that still provides grip.