labeck asks "I no longer live in a big city (was living in Chicago and San Francisco), so am blessed with extra space in my 1BR that has vaulted ceilings and a long walk-in closet. Because I had so much space, I was lazy at creating homes for belongings and just tossed things on various shelves in various places. So my apartment appears relatively clutter free but I know that the piles and items without homes are everywhere. How did you create homes for things?"
Sort your things into categories; sports equipment, personal memorabilia, travel items, misc household (like extra decorative pieces), etc. This key. Grouping things of the same category makes it easier to remember when you need to retrieve and put things back.
Once sorted, you can see how much space each category takes up helping you figure which closet or room it can easily fit and be taken in and out when needed. Make sure you put heavier things on lower shelves or the floor and lighter things on upper shelves to avoid hurting yourself or damaging anything when moving. Label boxes so you don't have to remember what's in there.
When applicable, keep things nearest to where it will be used, like off season clothes on the upper shelves on your clothes closet, and infrequently used kitchen items/appliances on the upper most shelves in the kitchen.