Instructions
Hold the Glock in your non-shooting hand and form a "V" with your shooting hand, between your thumb and forefinger.
Place your Glock within the "V" so that it is aligned with your arm. Secure the grip with your three lower fingers and rest your thumb alongside the pistol (your thumb should act as a backrest and exert no pressure).
Determine the amount of pressure for a proper grip by squeezing the Glock until your hand begins to tremble. Relax the pressure until your hand no longer trembles; that is the proper amount of pressure for a good hold on your pistol.
Position the first digit of your trigger finger on the trigger so that you can smoothly pull the trigger.