Anyone who's been in marketing for more than a day understands the value of customer testimonials. Better than any other form of proof (logical argument, data, endorsements), they can prove particular claims that the marketer wants to make about his product.

But, like any marketing tool, the strength of a testimonial is greatly related to the effectiveness of its presentation. If you give your customers typical testimonials in a typical way, they will have very little effect, because they will neither attract attention nor deliver an emotional message. But if you can find a way to make the testimonial new - either with the language itself or with the presentation - the effect can be powerful.

When I teach young copywriters the power of proving their claims, I stress the importance of not using testimonials that "sound like" testimonials. When a customer tells you that your product is "far and away the leader in its field" or "the best thing since sliced bread," you may be thrilled because it sounds like something you might have written yourself. But that's precisely why you shouldn't use it.

The best testimonials are those worded in a way that catches your attention, conveys a positive message, and does so with credibility. "Damn good eatin' fish!" is a testimonial I'd much rather use than "Succulent and tasty." The "damn" arrests my attention, the choice of words is believable, and the effect of making "eating" an adjective conveys an immediate benefit. It almost makes the mouth water.

So that is one thing - selecting, finding, or creating language that meets these criteria:

* attracts attention
* conveys a benefit
* achieves credibility

But that's not all. To make your testimonials do their job, they need to be presented in a format that supports those three objectives. In a sales letter, for example, testimonials are typically presented as one- or two-sentence quotations that are placed either in the text itself or at the margins. If you have a bunch of one- or two-sentence testimonials, it doesn't hurt to use them that way.

But if you have a really good testimonial, one that's distinctive and believable and strongly conveys the chief benefit of your product, you should find a more creative way to present it. You can, for example, turn it into a big bold headline and bolster it with an eye-catching photo of the customer enjoying the benefit.

Perhaps the best way to achieve both powerful, unique language and a captivating presentation is to show actual customers in their natural environment speaking their own words. Infomercials selling wealth-building programs often present real customers talking about their success, but they are usually in a staged setting - in front of the beach or a swimming pool - and their comments seem to have been coached out of them. A much better approach would be to have these people walking around their homes or businesses, interacting with other people and talking candidly and in an unrehearsed way about how their lives changed by following the system that is being sold.

Home Depot just released three commercials that do a very good job of this. So good, in fact, that I'd recommend you study them to get an idea about what is possible - particularly nowadays, when just about every business should be working in mixed media, incorporating video into their advertising program.

Home Depot's new commercials feature documentary-like accounts of customers who have fixed up their homes. One features an African-American mother, her sister, her daughter, and her son. Seated in front of her children and beside her sister, the mother is obviously proud of the painting and spackling job she did on the living room. She says something like, "Now my kids say Mom did this and Mom did that"... and is interrupted by her daughter saying, "At first we were, 'Mom, you're messing up the house.'" The commercial flashes back to the mother getting tips on spackling at Home Depot and features impressive before-and-after shots. It ends with the mother saying, "This is a building that I made into a home."

Another one begins with a young mother saying something like, "I'm going to try to tell this story without crying." And then, "Two weeks after I bought my house, Dad died. He remodeled every house we ever lived in." And then she starts crying.

According to a review of the ad series by Stuart Elliott in The Wall Street Journal, the commercials were directed by Jeff Bednarz, a documentary filmmaker. "We started with the notion that nobody can tell a home-improvement story better than the customer can," said Gary Gibson, creative head of the Richards Group, the ad agency handling the Home Depot account. "They tell them better than we write them."

I agree. The message of these little films is empowerment and the effect is sentimental - but that sentiment is successful because it comes without a script and without professional actors. The cinema verite style that Bednarz chose to depict the customers' stories makes them at once dramatic and believable.

The bottom line is this: Testimonials work well if they are true - and the closer you can get to truth, the stronger your sales message will be. When working with testimonials, ask yourself, "How can I show this customer experience as dramatically and truly as possible?" You'll get a much better response.

Michael Masterson has developed a loyal following through his writings in Early to Rise, an e-newsletter published by Agora, Inc. that mentors more than 160,000 success-oriented individuals to help them achieve their financial goals.