A Closet Makeover

As I went through the mess that is Madelyn's closet, I realized I've got to find a good way to organize it - and organize it fast as more clothes are added to it almost daily. As I packed up Anna's clothes a year and a half ago I took the frugal approach and decided to use Ziploc Big Bags rather than plastic storage containers. At the time it seemed like a good idea, but now as I look at the bags in Madelyn's closet that are falling over and busting at the seams, I'm not so sure. I have also come to two realizations: #1 the clothes that come out don't look nearly as nice as I remember them when they went in and #2 I have no clue what is in the bags! Any suggestions on the best way to tackle this? By size, by season?