Good luck and have fun!
Even with 12U TB, I try to keep 2 goals in mind for every practice...Have fun. Get better.
Spent most of the day writing and re-writing my practice plan, and I think I'm ready to go!
And don't be afraid of tearing it up and throwing it away once you get to the field. You never know how fast they'll pick up things until you're there.
Keep it simple. Work on two things at practice, maybe three. Most of the time with the attention span at that age it's really hard to keep them fully engaged for too long.
Have fun!!! But most importantly, make sure they are having fun. Tons and tons of encouragement.