therapist - go to whichever one makes you feel comfortable, as long as they have a certificate saying they know how to use the machine, and have worked as a therapist for at least a month, you should be fine. Don't expect them to be nutritional experts, do that research on your own. Just make sure you feel comfortable enough to go thru the experience with them.
I prefer doing my own enemas now, and the stupid AMA made colonics
illegal here in CA anyway. sheesh. They should have a discount if you buy a group of colonics. If you're just starting, go once a week for a month, while taking cleansing herbs and super green.
You should see an immediate increase in energy, altho you may go thru a healing crisis first. Depends on where you are with your health. Skin issues should start clearing up, for instance.
As for naturpathic doctors, they should have a diet and cleansing regimen all printed out as handouts that htey advise for most people, since we most all have the same issues. They should have supplements and enema buckets available for purchase, or they're not thorough. Some great ones know how to do kinesiology and dark-field microscopy of blood, which I highly recommend.