When looking for the perfect storage container consider everything in a particular category you are wanting to store. Can you get all of it into one container? If the items are heavy, you may need two or more smaller bins. Do you need to see the contents? You may want labelled clear bins. However solid colours may be preferred, depending on the items.
Consider: How much space you have; measure before you go. What do you need to store? Test the stack-ability of the containers. How easy will they be to lift once they are filled?
When adding more items to your storage spaces always consider what you may no longer need, and keep the flow of in-and-out going.