try mixing the wheatgrass and the barley grass juice together, 1 or 2 ounces of each
The sweetness of the wheatgrass and the bitterness of the barley offset each other
also, mixing grass juice with a little bit of citrus juice like orange juice and/or lemon juice really seems to help with the flavor
Another thing I used to like to do is take 3 to 4 ounces of wheatgrass juice and put it in 1.5 L of water, and then slowly drink that over several hours. I just loved the feeling of that