Many books open with forewords, introductions, and acknowledgments; Harvey Mackay's best-seller Swim With the Sharks Without Being Eaten Alive opened with 15 pages of testimonials from everyone from President Gerald Ford to the Reverend Billy Graham.

The kicker? By the time the reader read those 15 pages, they were so convinced that the book would change their lives that what followed practically didn't matter.

Welcome to the power of the testimonial, a potent plug that can make people as much as seven times more likely to buy or try than if they saw a paid advertisement.

Email-based testimonials can be just as persuasive, but the key is to maximize their power. Here's how to do that...

Gather intel

There are many effective ways to garner beneficial testimonials for your brand. Email surveys and customer ratings are the leading way to accumulate textual testimonials, but don't discount the comments made to your customer-service staff.

If you are recording your customers' telephone conversations ("for training purposes" only, of course), you will likely discover a treasure trove of kudos and props. Simply contact those customers again and ask for permission to use their comments as testimonials while offering them a thank-you gift or discount.

The policy of providing incentives for testimonials can bear considerable fruit in the video arena as well. Now that anyone with a webcam, single-lens reflex (SLR) camera, or cell phone can record a video, many of your customers may jump at the opportunity to broadcast their opinions on your website.

The incentive you provide should be substantial enough to trigger response, but not so lucrative that you are giving the impression you are paying for testimonials. Your prospects will respect the testimonial only if they believe that it is honest and essentially uncompensated.

Lead the way

The most successful testimonial results are provided by open-ended leading questions, such as:

• How did you first locate us?
• Why did you seek us out?
• Did you have any uncertainty or misgivings?
• How was your overall experience?
• What issue did our product or service solve for you?
• To whom would you recommend us?
• What is the most important thing people should know about us?
• How would you rate us?

Those questions cannot be answered by a Yes or No and are constructed to elicit a particular type of response. Whoever is answering those questions will feel compelled to discuss your brand to a greater extent, and likely in a favorable light.

Keep it brief

Although most users will give an email, website, or other online display the benefit of approximately six seconds to capture their attention before they tune out and head elsewhere, Dr. Gitte Lindgaard at Carleton University in Ottawa has determined that a person can make an approximate determination about the visual appeal of a page in about one-twentieth of a second.

The caveat is that the testimonial has to be powerful and must get to the point at lightning speed: No loquacious rambling allowed. There are no hard-and-fast rules, but if you can edit the testimonial down to 35 or fewer strongly indicative words, you should fall within the limit of the average attention span.

Testimonial videos are also subject to attention limitations. The online generation was brought up on the 30-second commercial, thus they apply that guideline to the videos they view.

Unless there is considerable action or an interesting sequential demonstration, a talking head extolling the virtues of your brand will start losing viewers at the half-minute mark, and precious few spectators will be left at the end of the first minute.

Seal the deal

The essence of a testimonial is the acknowledgment of a unique experience. "I ordered it, I paid for it, I got it three days later" is not unique. There has to be an exceptional element that will convince consumers to want to emulate the testifier's experience.

As long as customers providing the testimonials are aware that their submission is subject to editing, feel free to distill their statement to the nucleus of greatest impact.

In testimonials, as in stand-up comedy, it's imperative to get to the punch line, so boil down the testimonial to its most powerful and "punchy" part: What was it about a particular customer's experience that will impress the general audience? Was it customer service over and above the call of duty? Was it a fast and hassle-free RMA (return merchandise authorization)? Was it a particular quality of the product or service that stood high above the competition?

It is imperative to keep the testimonial balanced and believable so that it does not veer over the line between effectiveness and hype. You also do not want to run afoul of the Federal Trade Commission's newly drafted draconian regulations on testimonial advertisements.

The authority of testimonials is a powerful advertising tool. Harness it astutely and glean considerable benefits.