When we moved last, I went through many things as I was packing, asking items "Do I love you enough to pack it, move it, and find a home for you in our new house?" I got rid of a lot of things when the answer was "No, I don't love you enough." And some items I said I did love enough are still in storage in our basement. When I go through them again, I'll have to ask the question of each item again!
I also ask if the cost of replacing the item if I need it again is greater or less than the cost (emotional and practical) of storing it.
For items for which we have many duplicates, I have the "How many of you do I really need?" question. Even when I don't actually get rid of all of the excess, I do separate them out--the primary ones to be used are easily reached, and the extras are store out of the way--sometimes to never come out, but that helps me prune them the next time I go through stuff.
I also do the "this is all the storage I have for these items" thing. For example, I have two armoires for fabric and sewing supplies, plus several plastic drawer units. That's all I have and I may not overflow them. If I want to buy more than will fit in them, I have to get rid of stuff to find room for them, because the sewing supplies are not allowed to overflow their allotted space.
(Now I need to come up with a working concept for my closet!)
Goal: Back to where I was!