TweetAgree, for the most part a natural senna laxative and a day of fasting and drinking water or tea is all you need. Most of the other stuff is gimmick.
Senna is cheap, effective and does not cause cramps at least for me. Also at moderate dose you do not get the bowl shredding butt explosions like many of the others. Hell, just the mag citrate like you do before a colonoscopy would be fine too.