The only hitting decision you will ever have to make is NOT to swing.
That's right. That's it. It's that simple. If you see your kid taking too many pitches, or fouling off pitches you think they should hit, then there is a great chance your kid is trying to do something different. What is your kid doing different? They are likely trying to decide between 2 options. They are trying to decide to swing or NOT to swing. All of this has to happen in less than a half of second. Good luck with that.
Elite hitters don't choose between swinging and not swinging in that half of second time frame. They are mentally and physically committed to swinging at every pitch. The elite hitters are already in swing mode. All they have to do is STOP. The only decision ever to make is STOP. Indecisive hitters take less aggressive swing, take too many pitches, and often will foul off good pitches they should hit. This also takes away from power at the plate.
Think about it! In batting practice is your kid in swing mode? Of course. Why? They are assuming every pitch will be a strike and in fact they are annoyed if the BP pitcher doesn't throw strikes. When a bad pitch is thrown they have the ability to stop. We need to transfer this mindset over to the game. I don't care what level of baseball you play, even the best sometimes get stuck trying to decide to swing or not. It leads to slumps.
It's really simple. Your hitter should be swinging until he is not swinging. If the hitter get's caught deciding between the two options the results will get worse especially against faster pitching. If he is facing slower pitching, this becomes less important because he or she has time to decide to swing. This is a great indication of why some hitters destroy a fastball and other hitters simply survive the fastball. It's the difference between aggression and reaction.
Stay in swing mode. You're swinging until you're not swinging.