Keep chemicals in their orginal containers. Do not consolidate containers. Flammable materials should be stored in an area which is away from heat, sparks, and open flames. Corrosive materials should be stored in an area that will not be severely damaged should a spill occur. Acids and bases attack wood and metal, and masonry and concrete to some extent.
Plastic offers the best resistance.
It is your best interest to dispose of hazardous waste as soon as possible. The hassles of caring for hazardous waste will no longer be your problem to deal with. In general, if an accidental spill or release of your quantity of hazardous waste at your site would constitute an emergency or major clean-up effort, you have to much and it is time to dispose of it.