How do you know if the content of your e-newsletter is on the mark? Answer: It depends on your goal.

If you're writing your e-newsletter as a communications and update tool, you'll measure your success by the kind of feedback you get.

Messages from readers such as “I loved the article in your latest issue” will be enough to make your day. But if the goal of your e-newsletter is to sell your product or service, then you're looking for a different reaction to your content: a purchase, either immediately or in the not-too-distant future.

The 3 Cs: Content, Community and Commerce

You might want to benchmark your newsletter against the three Cs: content, community and commerce. Remember them? At the height of the dot-com boom, the three Cs were the value proposition of every Internet business plan for a sticky Web site or portal.

They translate to an e-newsletter like this:

Digestible content

First, the content of your e-newsletter should be useful and relevant to your audience. It should be presented in digestible bites, offer food for thought and prompt readers to open your publication issue after issue.

A feel-good community

In addition, your content should make readers feel good about themselves. They should feel that they've made a wise choice by opening your latest email, that five minutes of reading time yielded an insight or best practice tip to use that day or tuck away for the next project.

This creates a sense of community, along with a distinctive, one-to-one voice. In fact, your most loyal readers may be contributing to your community by sending regular feedback or writing a guest article.

Commerce: propelling your reader to become a customer

Finally, you clearly present your subscribers with buying opportunities. If they know and trust you and your organization, they'll purchase from you, right?

Unfortunately, it doesn't always work that way. Good feelings are not enough to prompt a purchase through an email. Budgets and approvals stand in the way. You have to create a sense of urgency, a gotta-have-it-right-this-minute proposition.

Bottom line: you need a formula in order to add up the three Cs properly.

Offer your newsletter readers a loss-leader, whether it's a limited-time trial of your services or a low-price product. Get them to cross the threshold from reader to customer just once, and you can up-sell them later.

Adding up the three Cs: the formula that sells

So exactly what is the formula behind an e-newsletter or e-zine that consistently sells your products or services?

I spoke with Joan Stewart, aka The Publicity Hound, who has been publishing her eponymous e-zine (about how to get free publicity) for over three years; 173 issues and over 8,900 subscribers later, she's got a formula that works.

Following her advice to keep it short, here are her top five tips on how to sell through your e-newsletter:

1. Fanatical consistency

She is “absolutely fanatical” about publishing every week, including Christmas and New Year's. Thus, both the schedule and the content of her e-zine are predictable. Readers know what to expect—and when.

2. Problem = Product

By listening carefully to feedback and questions from her subscribers (a mix of corporate and small business), she knows what problems they are facing. “Readers get bored if you promote the same product week after week,” Joan says. “They have different problems they want to solve so you have to have different products that offer a variety of solutions.”

She now has over 100 products in her online store. Mainly, digital special reports along with audiotapes and CDs (the latter are derived from her teleseminars). “That's over 100 problems I can offer free advice on in my newsletter.”

3. Extract 3-5 content tips from a product

When she's planning an issue of her e-zine, she selects a product that she wants to promote. It can be new or two years old. She extracts from it “anywhere from 3 to 5 content-rich tips that people can use and benefit from, even if they never want to spend a penny with me.” She writes a mini article (200-300 words) incorporating those tips.

4. Pair content with promotion

After this feature, she pitches the product “in one short paragraph” (100 words or less). She uses a lead-in such as, “Need more help solving this problem? Need more ideas? Check out [product title].” Then she links to that specific product page on her site.

Most of her products are in the $29.95 range. She may also bundle several products together or offer a special 20-30% off promotion.

A former journalist herself, Joan's writing style is clear and succinct. When she makes the “ask,” it comes across as a natural progression of the content preceding it. There's no hard sell.

In a nutshell, this is her secret formula: free advice paired with a product.

5. Sell easy-to-create products

One mistake that a lot of would-be information publishers make, Joan emphasizes, is to spend months creating one high-priced product. Don't, she says! “The more narrowly you can define your topic, the more you can sell. But to do that you have to have a lot of products.”

She can crank out a special report “in one afternoon” on a topic related to free publicity. They're generally five dense pages: “an inch wide and a mile deep,” as she puts it.

Joan publishes The Publicity Hound every Tuesday in a no-frills, text-only format. She says she's busy filling orders Tuesday and Wednesday. And they're still trickling in on Thursday and Friday. Then her week starts over….

In 2004 she wants to surpass her monthly record of over $12,000 in sales of products and consulting.

Bonus Tip: browse over 40 “free articles” on her site. Note that in each one she has links leading to related products. It's the same formula: content + promotion.