Some quotes from the chapter "Grip Management (recoil control)" from Mike Seeklanders excellent book "Your Competition Handgun Training Program":
- Leverage: "Both strong hand and support hand must be placed as high on the grip of the handgun as possible."
- Friction: "we maximize out skin contact with the grip panels"
- Pressure areas: "The key area is the back of the gun (back strap)." "The support hand should be the gripping hand that applies the most pressure."
PS: I press with the ball of the thumb of my support hand on the grip. This increases friction.