Run to First
This piece of advice may sound silly at first, but remember to include drills where your batters are hitting the ball then running to first. So many times we get caught up in running the players through different types of batting stations that they are only hitting and never hit, then run.
However in the game, they not only have to hit the ball, they have to run to first as quickly as possible too. If you never practice this, you're batters may not be getting out of the box as quickly as they could. You may even see a slight pause between the hit and the run down to first. Just remember to have them practice what they will actually be doing in a game every now and then. It doesn't even need to be off live pitching.
Heck, you don't even have to have them actually hit a ball. You can line them up with thundersticks or speed bats (or lengths of pvc pipe even) at home plate and have each player swing then run down the line to first base and do this as part of your baserunning practice.
Just make sure batters have their helmets down and they give the player in the box enough room to swing and discard the bat. Do not let the players waiting for their turn be right up on the player swinging.