I found some small plastic bins at Target that are about 5" deep--just right to fit into the overhead storage areas in the front and back. I think we have 6 bins in each area. I labeled them (snacks, toiletries, DVDs, etc.) so everything is easy to locate.
We have four shelves in our closet and each one has a designated purpose.
Under the dinette seat on the kitchen side we have a collapsible crate that holds a week's worth of soft drinks and bottled water. We take out a few at a time to put in the fridge
Under the other dinette seat, where the water tank is located, we store a small broom, folding step stool, cube heater, etc.
We keep a tool kit, leveling blocks & wheel chocks under the front seat next to the door. We put an access door so we can get these out without having to pick up the cushion.
We have a camper shell on our truck, so we can put a large plastic storage bin there for anything that doesn't fit in the camper itself.
It takes a lot of trial and error to find what works for you. I'm sure you'll get lots of ideas from the forum. Have fun and pack light!