Some additional (and possibly repeated) things you need to practice in base running:
1. Running through 1st base and breaking the run down while looking right (for past ball)...
3. Picking up the coach at 3rd when going from 1st to 2nd (give out a number with hand after they have left 1st and have player call it out before they round 2nd)...
The mechanics of how to round the bases the correct way is very important and needs to be worked on but to me the biggest issue I see that hurts base running is not teaching them how to read the ball. They heard in 8U that they need to freeze on a popup or go half way on a fly ball and some just can't get those instructions out of their head.
They need to be able to read the ball in the air and determine if it will be caught. I've seen balls that were 50 feet over the OF head and the kid is just frozen half way on it. Or the little bloopers where it's clearly not going be caught and they freeze and get thrown out at second when they could have been on third.
Another one is the fly ball to the OF. If you are on first and it's a shot to deep left that may or may not be caught you need to be much closer to second versus half way. If they catch it you can still go back, but if it's over their head you get to score or get to third.
The final one at all ages is teaching how to score on a PB. It needs to be worked on so they can read the bounce while they get their secondary.
Good points, but hard to teach, especially to 10 - 13 year olds... Some have the attention span of a fruit-fly and about that much memory. Skull sessions at this age are not always as effective as they can be with older players (at least in my experience). It's great to talk about these situations, it's just hard to teach the minutia (sp?) and different situations that can happen on the base paths. It has to be drilled and drilled and drilled again. Are there any effective ways to drill all of these finer points that you've run across?