You do need an extracting type Juicer to get juice out of Grass.
We own and love a Green Life (now called Green Star) juicer. It makes easy work of this.
Cut and wash ingredients. Feed through juicer.
You can refrigerate juice but it never tastes better than it does when just made, and it tastes absolutely amazing then.
Wheat Grass juice is as closer in composition to blood than anything. When you drink it you feel it immediately! It is a very intense, and for many people a not too pleasant taste. We often drink it straight but we sometimes prefer it mixed.
Mix in any proportion you enjoy most. Buckwheat Lettuce is the mildest flavor so you might consider starting like this: 50% Buckwheat, 40% Sunflower, 10% Grass.
Hey, did you know that us Sproutpeople took that picture of Wheat Grass Juice? We did - over a decade ago. We see it all over the web nowadays. We're flattered so many have copied it!