I am a big advocate of avoiding the use of paper or plastic bags when shopping but I have had such a hard time remembering to use the green bags. I forget to put them in my car or bring them with me. I have found the solution for me. I got a chico bag as a favor from a work thing I went to. It's small and packs into it's own bag and I keep it in my purse. I have used it countless times already so I got myself another one tonight at Whole Foods. These I can remember to use. It feels nice to know I'm keeping plastic bags out of the landfill and not contributing to the need for the production of paper bags.
I definitely reccomend getting one if you have trouble remembering to bring your bags along to the store.