For collard juice, I use a little bit of 100% apple juice (no sugar or preservatives) just to get the blending process going and to help mask the bitter taste of the collards a little. You can use any liquid you want but I find that apple juice to be the best tasting. For fruits and vegetables that have higher water content you may not need any extra fluid at all.
The video is pretty much self explanitory. I figured for my first instructable I should keep it simple. Hope everyone enjoys!