Unplug the microwave if you plan on using it for storage. You don't want anyone to accidentally hit a few buttons and start nuking things you didn't intend to receive such extreme heat.
Spray the inside of the microwave with an all-purpose cleaner. Wipe it down with a sponge, removing caked-on food and crumbs or dust. You want this to be a clean storage space.
Store baked items like bread, biscuits, cookies and rolls in the microwave, as it offers such foods airtight storage. Dry goods such as rice, cake mixes, pancake mixes, pasta, beans and other foods will also keep well in the microwave. Alternatively, stack large plastic bowls on top of each other or cutting boards or other unwieldy items and hide them out of sight in the microwave