First, and most important, always follow good, basic consumer techniques. Read everything before you sign. Don't be pressured into making hasty decisions and purchases. Remember that if something sounds too good to be true, it probably isn't true. If someone or an organization is pushing a new health care product, check with your doctor before sending money.
Unproved products can be dangerous as well as a waste of money.
If you call or write them, that's one story. But if they initiate contacts, you have the right to be suspicious. Even if you believe the person and the product are legitimate, take your time to read all the forms before making a decision. Ask the person to come back another day. A delay, during which time you are checking credentials and references, may dissuade con artists from targeting you.