I've done the one in, one out method for quite a while now for clothing.

Over the past 3 years, anticipating a potential move to a much smaller apartment out of state (where the cost is by tare weight), I've been giving away tons of stuff: books to the Free Library and public library; clothes to a local non-profit that gives clothes away to low-income students and families, or to Goodwill or Planet Aid; and dozens of other art supplies, kitchen stuff, and on and on via Freecycle. I occasionally can sell something.

I'm saving this article for some other good ideas I hadn't considered.

I have found that learning about how others have been using my castoffs makes it easier to let things go. https://medium.com/crows-feet/sparking-joy-4c31c8d4b34d