Dry fire sight picture and trigger control practice can help a whole bunch. With an empty pistol, aim at a door knob and tighten your pinky finger while holding a normal sight picture. You'll notice the sights move. That's 'squeezing fingers'. Grasp the pistol like you're shaking hands with a firm grip, but not a crushing grip. Your trigger finger should not be part of the grip.
"...should pull the trigger with the tip of the finger..." Nope. Usually just in from the pad of your finger allows you to pull straight back. Using the tip will pull your shot off. And, if you can't get more finger on the trigger, it means the pistol is too big for your hand.
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