Before you cast away unwanted items of clothing, ask yourself if you could easily alter them to make them wearable. Have a pair of jeans that is now to short? Cut them off to make a pair of shorts to wear to the pool or beach. Is there a dress or top that you don't wear because you don't like the neck or sleeves? Try cutting the sleeves off or changing the neckline. This is a simple and easy way to go green.
I am fortunate enough to have a mom who is an amazing seamstress, and she has altered countless items for me over the years. (Thanks Mom!) Most recently, she hemmed a skirt for me that I've had for years. I like the pattern of the skirt, but it was at an awkward length. By shortening it several inches, it's now at a much more fashionable length. She also recently turned a floor length bridesmaid dress into a knee length cocktail dress. Yes, that's right. I actually shortened a bridesmaid dress and wore it again. Eat your heart out Katherine Heigl :)