Allow me to introduce you to the mysterious "E-Factor." It's mysterious because it has two meanings.

Both meanings will help you get more business from any promotion you do. So without further ado, here's how you can use the "E-Factor" to make more money:

• Put "E-Factor" in your testimonials and copy

Did you realize the very best source of new business is almost always a prospect who has been referred to you by a friend or trusted business advisor? It is. Think about this in your own life. When you need an accountant, or an attorney, or a doctor, or for that matter a hardware store in a new town, you'll probably turn to someone you know, whose judgment you trust, to refer you to the service or product provider you're looking for.

OK. But what does that have to do with direct mail and Web promotions?

A lot. People are always on the lookout for sources of advice they can trust. However, since you can't always rely on giving every prospect for your business personal recommendations from the prospect's friends, neighbors and advisors they actually know and trust, you do the next best thing: You give them copy with recommendations from people who seem like the people they know and trust.

How? By putting testimonials and case studies in your copy involving people who will fill the role of trusted friends and advisors.

Many marketers do this but they don't get the desired effect. Why? Because they haven't put enough productive effort into the research that pays off. This is in-person research --especially one-on-one "casual" research, as opposed to formal focus-group research--with their actual customers, and people who are a lot like their customers.

This high-payoff research gives you in-depth working understanding of how your prospects think and act in the world--and how they look at things and make decisions. When you have this understanding and you weave it into the language of your descriptive copy and your testimonial quotes, it's called "empathy."

"Empathy" --that's the first meaning of "The E-Factor." Increase empathy in your copy and you'll increase sales.

• Profit from the second meaning of the "E-Factor" as well

There's another, equally important meaning. Before I tell you what it is, let me give you a big, fat hint. In his book The Entertainment Economy: How Mega-Media Forces Are Transforming Our Lives, author Michael J. Wolfe points out that American consumers put 8.4%--about one dollar out of every 12--into some form of entertainment. Currently, that adds up to $480 billion a year.

As a side note, Hollywood productions--films and TV shows --bring in the second largest amount of money from overseas back into the U.S. economy, after aircraft sales.

Yes, the other meaning of the "E-Factor" is entertainment. It's huge. And it applies to marketing and selling. As the late (and great) David Ogilvy reminded us, "People will not be bored into buying."

But beware. Many a copywriter less talented and, more importantly, less thoughtful than Mr. Ogilvy has made the fatal error including humor, fantasy, drama or thrills in a promotion in such a way as to not specifically move the sales process forward.

And that's dangerous. Even deadly, sometimes. Here's why: When you include entertainment, people's attention will invariably be drawn to it over anything else. And when entertainment does not directly support moving the sale forward, then it automatically detracts from the sale.

There are dozens of examples. The lying Isuzu salesman. Sales went down. "Plop-plop, Fizz-fizz." Sales went down. I'm sure you have your favorites of entertaining ad campaigns that bombed. Now you know why.

Entertainment isn't bad. But not painstakingly linking the entertainment to the forward motion of the sale is bad. Very bad.

So… how do you add entertainment value in such a way as to increase the sales effectiveness of your promotion? Several ways:

• Tell a dramatic story where your product is the hero and saves the day for the human involved. My favorite example of this is the newspaper ad for Joe Karbo's legendary book "The Lazy Man's Way to Riches."

In the ad, Mr. Karbo talks about his "Lazy Man's Way" which he promises to reveal in the book he's selling. He tells how, before he knew the "Lazy Man's Way," he used to work 18-hour days, 7-day weeks and was still perpetually in debt. But after he learned the "Lazy Man's Way," he became financially independent by working less and in fact became very wealthy.

This incredible ad combines drama with sales power in an unbeatable way. And it worked! The ad sold 3 million books by mail order!

• Use humor that adds emphasis to the value of your product or service. When you get past the laughter, most humor in ads just shows off the cleverness of the creative team who created the ad. (You might say it also shows off their lack of concern for creating sales.) A positive example, where the humor shows how the product is so worthwhile, is the old (and very successful) series of Seinfeld commercials for the American Express Card.

• Use exciting, colorful language in testimonials when customers are talking about the virtues of your product. But make sure it's believable. And don't make fun of the fact that you're selling something, any more than you would go to target practice and fire the first shot into your own foot. At all times, keep your eye on the target--increased sales!

So let's review. How can you use this information to make more sales in every promotion? Take stock of its Empathy and Entertainment Value. Be single-minded. Take out everything that takes away from the sale, and keep in--or boost and strengthen--everything that furthers the sale. Build the strongest possible promotion at every point along the way… and watch your response rate soar!

David Garfinkel is widely recognized by many "marketing gurus" as their secret weapon. That is, he is known as "The World's Greatest Copywriting Coach"; because, he can, like no other, teach you how to turn words into cash.

David is also the author and narrator of Killer Copy Tactics, the Web's first and only totally interactive audio / visual learning system for writing killer sales copy. You can master these killer copy tactics by clicking here to discover the secrets of how you can write killer copy.