It helped me to think of gripping the gun tight in the back (top, bottom, left, right), instead of hard per se. Probably because I have the strength of a 14 year old girl.
I eventually noticed the bottom of my palm slightly peeling off (not really, just less pressure), then my pinky would grip tighter at fire. I was gripping hard on top, just my pinky wasn't. To make matters worse I could keep the sights steady and press the trigger straight back when dry firing even when the grip wasn't tight on the bottom. Then I'd shoot live fire, or a match, and discovered that my pinkie would squeeze harder into the bottom of my palm. So now I think thumb-palm as a padded U-shaped plate and make sure there is equal-pressure behind the gun. I even had to re-learn the trigger press because it felt different after the correction.
It's funny that the title is "pushing" the gun down, because I was actually pulling it down. Kind of like milking the gun, only just with the picky.