I've been trying to be better lately about not buying things that aren't really necessary. I hardly ever buy magazines anymore, and seldom buy physical books. I do buy a few ebooks, but they don't take up much space. ;)
I've also been trying to get rid of stuff that I don't need, and never look at. Last year I sold a bunch of yarn from my considerable stash, and lately I've slowly been selling my old knitting magazines on eBay, Etsy, and Amazon, and books on Half.com and Amazon. It's terribly satisfying to list a 10 year old magazine that I paid $5.99 for, and sell it for $19.95. Last weekend I was down in the basement looking for something, and found a deck of miniature animal totem "medicine cards" that looked like they'd never been used. Just on a whim I looked them up on Amazon. They're out of print and, amazingly, there were people who had them listed for sale for over $150! Of course, that doesn't mean that they're actually selling them for that.
The cheapest one on offer was listed at $75.00. I decided not to be greedy, and listed mine for $45, and they sold tonight. I've been going to the post office every night this week with a couple of packages. It gives me some extra spending money, and clears stuff out of the house, neither of which is a bad thing.
I've yet to find anything of immense value, but you never know. And selling an old magazine for 3 or 4 times what I paid for it isn't bad.