To piggy-back on Zebraman's last post, I have made sure that the last thin I mention in the pregame conf is the coaching box. This way, it stays the freshest on their minds throughout the game.
I have had to give one warning so far this season (eight games), because the coaches are more aware of the box now. Just a quick glance over most times will do the trick. It's is funny to watch a coach dance around trying to stretch the boundary in the name of 'coaching'.