Get rid of things you don't need.
Get a bunch of those big Rubbermaid tubs with lids. They stack. Build a bunch of shelves to fit said tubs. THen everything goes away (a) organized (b) labelled (c) dry (d) retrievable.
And throw out the broken reindeers, the cracked easter-baskets, the switchless weedeater, the tires you don't have a car to match, that sports equipment no one has used since 1966... etc.