Shooting a handgun is a learned skill. It takes dedicated practice and hours at the range to adequately learn how to shoot.
Obviously, the first thing to learn is how to hold a handgun.
Regardless of what you may see in movies and how cool actors may look, a two-handed grip is the best way to shoot- especially for beginners. This ensures optimal stability and control. With this, your dominant hand should grip the gun high on the back of the grip on the gun to ensure more leverage against the weapon in the event of recoil.
Your other hand should be pressed firmly against the exposed portion of the grip not covered by the gun hand with all four fingers under the trigger guard. Both hands should be high as possible on the grip with the thumb pointing forward.
When taking aim, stand with your feet and hips shoulder width apart and bend your knees slightly.
Using your dominant eye, aim at your target, aligning your front sight and rear sight notch found along the top side of the barrel. Ensuring your sites are accurately aligned, there should be equal amounts of empty space on both sides of the front sight.
Now you are ready to fire the weapon at your target. When ready to fire, press the trigger in a controlled fashion straight to the rear. Applying constant, increasing rearward pressure on the trigger until the weapon fires guarantees little disruption to your aim.