Plastic Dividers with Pockets
I put all of my lesson plans into plastic sleeves. I also put any copy "masters" in a plastic sleeve right behind the lesson plans. I keep my sub folder stocked with all the copies a sub might need for one day. The sub plans the copies go in the pockets for that grade level. My subs don't have to hunt for papers any more.
I've discovered that brand DOES matter! My Avery pocket dividers have lasted for more than 5 years. My off brand pocket dividers aren't going to make it through the year.