Holster the gun empty...hammer down. As your hand starts to aquire the pistol...fingers against the frontstrap, cock the hammer with your thumb...not with the pad...but with the the joint, or just below the joint. You roll the hammer back with your hand executing a rearward rocking motion. Done correctly, the pad of your thumb should now be hooked and bearing down onto the hammer face, and actually holding it past full cock...spur touching the grip safety...as you begin to pull the pistol from the holster.
For safety's sake, your thunb should ramain hooked with the pad bearing on the hammer until the pistol is well clear of the leather...at which time, the thumb moves off the hammer into the natural firing position...and your finger enters the trigger guard as the gun moves through the arc toward the target.
With a little practice, it becomes smooth and surprisingly fast, and as long as the thumb pad remains on the face of the hammer, you have a "safety" that blocks the hammer so that...even if you unintentionally touch the trigger...the hammer can't drop unless you slide your thumb off of it while the trigger is pulled. Even if the pad of your thumb slips, you still have the area under the joint applying pressure and friction against the top of the hammer spur, which slows the hammer should it get away from you, making an AD less likely.
With the hammer, cocked correctly as described above...you'd almost have to try to unintentionally fire the gun...which would make it intentional.
Work with it a little...gun empty...then with primed, empty cases to let you understand how hard it would be to get the gun to fire without meaning to.
I've taught this method to several people who remain unconvinced that the 1911 is safe to carry in Condition 1...and they've come to be proficient with presenting the gun, and a few have become wicked fast using it.
To decock the hammer...reverse the cocking motion. Hook your thumb and place the pad on the hammer face. Pull the hammer past full cock to insure that you have control of it. Pull the trigger, and roll the hammer down by slowly straightening your thumb, maintaining downward pressure on the spur. Keep your thumb hooked a little, to keep some of the pad between the hammer face and the slide. If you have small hands, you may want to use your weak hand to give you better control, and to depress the grip safety...but pulling the hammer spur against the grip safety usually disengages it unless you have a high upswept grip safety and a rowel hammer.
People with normal to large hands can cock and decock the pistol one-handed all day long without incident...but practice it dry to find your sweet spot. Every hand is different.