For me, the Beauty of playing with a box call is figuring out it's personality. The way that I play a box call all depends on how the box call wants to be played. Finding the sweet spot is the first thing that I do. In addition to finding the sweet spot on the sides of the box, I also play around with using my fingers on the lower section of the sides, instead of just holding the bottom of the call, let your hand wrap around it some. In most cases applying pressure to the sides of a box call will deaden the sound.
"Instruments of Mass Destruction"