My newest method is an idea from Pinterest to use over the door shoe organizers to store my therapy materials. I have been loving this! I have been loading up the organizer once per month to include themes for holidays and books I'm using. I have each section categorized so that I always have something for following directions, articulation, at-home practice, turn-taking games and any other typical goals for my students. Having the materials handy has been a lifesaver.
And you know those little calling cards to go with your BINGO games? I use a binder ring to keep them all together.
For those materials that are just to big to keep in a little pocket, I use a small bookcase to keep everything together. Because let's face it, preschoolers are not known for their patience while you find what you are looking for.