When I buy kale or chard I like to wash the greens when I get home from the store. After shaking off excess water I place them in an overlapping single layer on top of a cloth or paper towel. If I have enough greens I place a second towel on top of the first stack and top with another layer of greens. Then I roll the towel into a tight bundle. This keeps the greens fresh and crisp for up to a week.