I make a very simple green smoothie. There are better ways of making them that add more nutrition, but I like it simple and cheap.
Place a handful of spinach in a blender. Add yogurt. Then pile in some fruit. I use anything I have on hand; this may be fresh, frozen, or canned. I like using at least 3 different types of fruit. Then I blend it up real well. If it's too thick, I add juice or milk. If it's not sweet enough I add honey. Enjoy!
Tip: If you add fruit, you can't taste the spinach at all.