If you are right handed, this is a classic case of jerking the trigger. Focus upon trigger control and stare at the front sight. Make sure that the center of the pad of your finger is on the trigger. Also make sure that no part of your finger drags against the frame while shooting.
Your grip is especially important. Make sure your off hand is wrapped nicely around your primary hand. The index finger should be touching the bottom of the trigger guard. Both thumbs should be pointing forward on the same side (and should just lightly touch the frame). Push forward through your should directly down the line of the bore. At the same time, pull from the shoulder through your offhand directly through the axis of the bore. Push and pull as hard as possible until you start to shake, then back off until the shaking stops. The level of pressure is different for each pistol. By pushing and pulling, you get 1) a more stable platform, 2) better recoil management, and 3) more even pressure all around the grip.