Tee Work
Tee work is another great way to work on simple hitting mechanics. However, it comes with a caveat. Most younger players, and many older players think hitting off a tee is about blasting the ball and tee as hard as possible. Some also find tee work boring and do not take it seriously.
Set up the tee so that it sits on the front part of a home plate. As a hitter, we want to hit the ball out in front of the plate, so this simulates it as such.
Make sure the batter is comfortable in their stance. Pay close attention to the timing of their hips, arms and legs. The hips should open up to the pitcher as soon as the arms are coming through. The batter should turn on both feet. If the feet are not turning right, you can slightly cheat them with a "pigeon-toed" stance to begin with.
You can do this against a fence, or with fielders in place.