Anyway, I feel like this post is still fine for today, since there's not really a bad time to think about the environment. I actually wrote something similar last year when I was taking my green design class at school, but I liked it a lot and wanted to do it again. There are a lot of ways to go green when you decorate, so this is far from a comprehensive list, but these are my favorites at the moment. If I missed something you like to do, feel free to share it in the comments.
Buy antique/vintage furniture. Not only is it pretty, but it's hecka sturdy. Back in the day, there wasn't the abundance of cheap-o furniture we have now, which means fewer things were tossed in the landfill after a leg fell off. (You know I love me some IKEA, but let's be real: that stuff isn't intended to last the rest of your life.) Antique furniture is higher quality than most of the stuff made today, so buying it means you probably won't have to replace it. A subset of this is to buy secondhand furniture on Craigslist/at Goodwill/whatevs, but since I just came back from the East coast where the antiques are EPIC and so much older than what we have in Chicago, I'm all googly-eyed about the real thing.
Make it work. Try to do a Tim Gunn on your existing furniture and accessories before you run out and buy something new. The Power of Paint goes a long way, but depending on the specific item you could also change the hardware, recover the seat, or sand and re-stain--which I'm terrible at, but maybe your relationship with stain is better than mine. For extra green points, you can try to use materials you already have around the house.
Be careful with trends. Wallpaper, for example, is a double-edged sword. It can look SO COOL, buuuuut the trouble with going really trendy is that you might not like it in a few years... and will then want to rip it all down and start over. I like the idea of doing a bold area rug instead, because if you do get sick of it, it's way easier to pass on to somebody else than a pile of shredded wallpaper.
Downsize. This one is OBVIOUSLY the most extreme and people can't just move at the drop of a hat, but if you ARE in the market for new living quarters, going smaller is a plus for all sorts of reasons. Little homes use less energy (which makes them cheaper to heat and cool!), there's less space to keep clean, and having less storage space means a hoard won't sneak up on you. Not that you need to shack up in a tiny house, but even going 25% smaller will make a difference.
BONUS: Add some indoor plants. This was something I didn't think about until I took my green design class last year, but the indoor air quality in your house might be kind of iffy. Adding a couple of air-purifying plants will help cut down on the VOCs floating around. I need to find one that will be impossible to kill. Too bad cacti weren't on that list...
So what do you do to be green around the house? There are also non-decorating things like composting, recycling, growing a garden without killing all of the vegetables, using natural cleaning supplies... Tons of options! What's on your list? Did you do anything cool for Earth Day?