We use those plastic folders with brads from Walmart.
I have a pencil pouch for transportation of notes and money (so it won't slip out!), a 9 week grading period behavior calendar, and their parent-signed behavior contract behind that. Our kinder teachers have a communication log in there too. Handouts from the office go in there as well as notes that need to be sent home and finished/"graded" classwork. I always put my personal notes from me in the zipper pouch so they won't get lost but the other handouts go in the pockets. I stress to parents to clean out folders every night because I don't have time to go through their folders and look for something I am expecting returned.