Amy in AZ: Agree! I often used to say, "FEET, Hips, THEN Hands" - now I generally tell them get their wheel started early or get the front foot down to heel plant earlier...
Drive through the ball, EXPLODE through Contact! (sometimes, Contact to extension, cause my girls know what I mean as we've worked hard on the contact point and staying on the ball through extension.......
I like the Snap to Extension..... I'll steal that..... cause we do teach to snap pur wrists into contact, and that emphaizes the snap of the wrist and reminds them to stay on the ball through extension......
hands inside the ball
heel down, heel up (or foot down, foot up)
palm up, palm down
circular hand path
top hand torque
separation
quick to it, long through it
see it and hit it
hands back
wait on it
drive your legs
UCLA hole to China
snap your wrists
throw your hands forward
knob to the ball
hands to the ball
pull the the knob
I prefer to keep it very very simple. While all of the suggestions are good, sometimes what we say doesn't always mean the same thing to them as it does to us. I tell them, "You can't hit it if you can't see it". In other words, don't worry about having perfect form and motion. See the ball and then hit the ball.
OK, the two I use the most as reminders for kids when they are entering the batter's box is:
Gap to Gap!
Hit with the thick part of the bat!
For my child, "hit with the thick part of the bat," is what I say every time. She hits in the 3rd slot and is often pitched away. So, she had a spell where she wanted to crowd the plate and look away. That put the thin part of the bat over the plate for anything middle in. So, it reminds her to load her hips, let the ball get deep if it is outside and if it is inside, hit it hard.