One of the best investments I made for helping me to stay organized was purchasing baskets! When Michaels had one of their 50% off sales on baskets I picked up a bunch of these:
I use these baskets for everything. They measure 11" x 16" and 13" x 18". When I ran my summer camps and did stations, each station had a basket filled with everything needed for the week for that area. I just completed 2 workshops and each workshop had a basket which held everything I needed for that workshop. I am halfway through a weekly Pre-piano camp and this basket (11" x 16") shows most of the things we used for the last class (some are hidden underneath!). Once I have planned the event, I put everything I need in one of these baskets and then I can rest assured that I am completely prepared. No scrambling at the last minute, no piles that can fall over, no worries! And...they nestle within each other for easy storage when I'm not using them.
Love these! They make my life SO much easier!