Another way to help our planet is to make sure that the piece of furniture you are buying is built to last. If you think about the furniture in your grandparents house, it is old right? My grandparents have had the same one bedroom set since they got married. That's because the furniture back then was made to last through generations. Brikolör is a company that believes in the same philosophy. They are committed to producing furniture "with a guaranteed emotional and technical durability of 300 years." The Pärlan chair (below) is made of laminated turned solid ash.
Bamboo is a pretty popular material to use nowadays. While it is very sustainable because it grows almost as fast as grass, you have to think about where it is coming from and how much energy does it take to ship it. However, going green could mean that you have to compromise sometimes. Below is a much more comfortable bamboo chair than it actually looks , the "Bamboo Stomach" by PIE.
Another way to buy sustainable is to know how much material is being used to make you piece of furniture. A great sustainable design called the "Flat Chair" by Croatian designer Filip Gordon Frank is sliced out of one piece of plywood and folds completely flat. It uses as few material as possible and the way it is sliced means that no wood is wasted. It can also double function as an art piece when hung on the wall.
Finally, don't hesitate to recover an old piece of furniture and recycle it into a new modern twisted one. My personal favorite redesign of an old chair (and one of the item on my Christmas wish-list) is this chair by Fredrik Färg. This throne-like chair will make you feel like royalty sitting in it!