There are lots of variations that can be made to this basic green smoothie recipe. You can use a variety of fruits and greens, but the ratio should be:
1/3 water
1/3 greens (after blended)
1/3 fruit
I usually start with 2 cups of water in the blender, then pack the blender full of greens (kale and spinach are what I usually use). Throw in 1/4 of a lemon (rind and all). Blend it down and add more greens and keep blending until the total volume is 4 cups after it's blended. Then fill the rest of the blender with fruit and blend until smooth. I almost always add a banana or two and frozen berries. If you like it sweeter, you can add some chopped dates as well.