With fasting, there are several things that are important, such as keeping your bowels moving every day and being aware that you may need to slow down or stop your fast if you detox too rapidly. I like the books "Mucusless Diet" and "Rational Fasting" by Arnold Ehret.
I personally usually only drink fruit juices. For fasting, I like a mono-fruit juice; I use oranges. (I've also done the Master Cleanse). One food at a time is easiest on the digestive system.
After I learn how to grow barley grass or other grasses from seed, I'd enjoy learning how to use those for juicing as well.
Fruit juice fasting is the best thing I ever did for my health!