I would also practice trapping an offensive player who either has the dribble or has picked it up. This affects the intensity of the trap. When trapping a player who still has their dribble the two trapping defenders must overlap their interior legs to take away a dribble to split the trap. In the process however they must stay on the balls of their feet and with knees flexed or they will not be able to move the trapping pocket with a smaller quicker dribbler. This is critical if you are to be successful at trapping.
Most players lock their legs up once they have approached the offensive player being trapped.
You might consider creating a 13 yellow and 13 red command to signal whether or not the traps and help defenders should play cautiously or gamble at all costs late in game when only steals can get you back in a game you trail. Here are some basic rules for trapping that you will want to consider when teaching this defense. Teach your players to move with the flight of the ball. If two trapping players are moving toward a player who has released the ball in the opposite direction you will not be an effective trapping team. They must learn to arrive at the trap with the flight of an oncoming pass.