One of the things that my mom-in-law was impressed about my housekeeping is the way I keep the plastic shopping bag. Every after we unload the stuff in the bag, I would smoothen, fold it neatly, file them and keep them in a place where we can easily reach them anytime we need it.
I used to do this when I was till in the Philippines. Keeping them neatly folded does a lot of advantage. When you need a bag, you save trouble looking where they are and they are perfectly ready; no need to smoothen them. Carrying a badly crumpled plastic bag does not make a good impression. There are a lot of things that we may need the plastic bag, too. (I'm sorry to those who campaign about not using neither plastic nor paper in shopping anymore.)