usually all I do is grab a couple leaves of collard greens, dandelion greens, endive and escarole, wash them then chop them up. I put a paper towel into a sandwich bag and put the chopped greens into it, with another paper towel on top. This usually lasts me about 5 days before I have to make another batch. The paper towel absorbs moisture and keeps the greens from going bad before they are used up.
preparation time is about 5 minutes, so is perfect to do while waiting for a kettle to boil for coffee.
I don't use blenders as it typically turns the greens into a coarse mush and it doesn't take that long to finely chop up a few leaves of greens. The method I use may not work so well for people who have a large collection of dragons but works great if you have one or two.