It helps to be on a clean diet with lots of veggie juices but it's not mandatory. :) Oh wait, for really good health it is. ;)

General tips and tricks:

Massage the soles of the feet. This helps loosen things up so you can take in more water. I use a wooden foot roller.

K-y jelly is a great lubricator for the tip.

Try lying on your back and raising your buttocks at first. Press down on left side near ribs to force water in. Massage counter-clockwise.

Turn onto right side to help water across transverse colon.

Warm water is held in longer.

When you feel like you can't take in any more, stop the flow, take a couple dEEP breaths and try to take in more.

Hope that helps! :)