Another tip I've learned over the years is ... bring a small bottle of water with you, in your backpack (if you carry dekes, like I do).
BEFORE you use your mouth call for the very first time, put the call in your mouth, take a swig of water, and "swarsh" it around in your mouth for a good minute or two... Spit the water out when you're done... What I've found is that a totally wet mouth call sounds WAY better on your first call than a dry mouth call, just put in your mouth... Many times, the little rubber/latex things (aka reeds) stick together, and swishing the call around with water in your mouth loosens 'em up & gets the call ready to use.
Regarding storing your mouth calls, I use Scott Ellis' method right here -- which makes warming up the call in your mouth w/a little bit of water even MORE important to do...
Scott's mouth call storage video:
http://youtu.be/yve9ZkQZIwsBGD