When we moved into our new house we found that all the closets had wire shelves, which was fine, but the support system forced them to be a couple feet apart. So we installed a different shelf support system and doubled the available shelves. It’s also more modular, if we have to move things around.
And isn’t it amazing how much stuff you get rid of when you move?
We also tried the “less is more” technique. Remove everything from a small area, box it up, and only replace stuff as you need it. This helps immensely with decluttering and it’s amazing how much stuff never comes back out of those boxes, especially if it’s decorations.