When considering what to put in a storage unit, there are a few things you should avoid. First, do not store any flammable or combustible items. This includes gasoline, kerosene, oil-based paints, and propane tanks. Second, do not store any food or perishables as they will likely go bad over time. Third, do not store any dangerous chemicals or explosives such as pesticides, fertilizers, pool chemicals, and fireworks. Lastly, try to avoid storing anything that is valuable or sentimental as it could be damaged or stolen while in storage.