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How disobeying the “rule of one” mutilates sales

The “rule of one” is an important copywriting lesson coined by the great Joanna Wiebe. For those unfamiliar, Joanna founded Copyhackers and is a brilliant copywriter in her own right.

And y’know what?

Today, I wanna show you just how powerful this “rule of one” principle is. It could be the difference between a campaign that tanks—or one that makes close to 6 figures. Well, at least that’s the case in my experience.

So what’s the rule of one?

The rule of one states that every piece of copy you write should focus on…

* One big idea

* One reader

* One promise

* And one call-to-action

Too often, copywriters try to jam as many products into a particular email as possible. I’ve made this mistake too. It checks out logically — “more products = more sales” because people have more options. But buying ain’t a logical decision, cully, it’s an emotional one.

That’s right. In the world of copywriting, persuasion, and sales, your logic betrays you.

Instead, it’s more profitable—by orders of magnitude—to follow this “rule of one” against your own logic.

Lemme prove it.

One of my clients has an abundance of products in his store. I’m talking about over 600 products. Which is both a gift and a curse.

The gift? Well, we never run out of email ideas.

The curse? Well, even if we sent an email about a new product every single day, we still couldn’t promote all 600 products in a calendar year.

The solution? We enroll our list into a series of automated email campaigns. First, we speak about product categories for a few months — covering a myriad of categories and products.

Then, once they’re acclimated to our various product categories, we enroll them in another automated campaign where we speak only about one product per email.

Which set out automated campaigns do you think generates more revenue?

I’ll give you a hint:

In the first set of automations we disobey the “rule of one.” And in the second set of automation, we obey the “rule of one.”

And since I’m a big “facts over feeling” and “real life over theory” kinda guy, let’s see how this plays out in real life.

Our most successful category-based email automation series generated $27,651.79 from 6 emails. Not too shabby, but as you’ll see, it pales in comparison to the product-based email automations.

Our most successful product-based email automation series generated $75,557.95 from 7 emails. It had almost a 3x higher conversion rate than the most successful category-based automation.

And the best part?

It went out to more than 2,000 fewer people.

That’s the power of the “rule of one.”

And it’s a simple and actionable way to generate more moolah from your email campaigns.

Remember, you only want to focus on one big idea, one reader, one promise, and one call-to-action. Now, following this rule is easier said than done. Your brain will fight against it. You’ll be tempted to add a Klaviyo recommended product block that mentions 3-6 products.

But disobeying this rule can wreak havoc on your sales.


If you need help sending emails that follow the “rule of one” to an annoying degree (and makes you fat stacks of greenbacks in the process), book a discovery call with me below:

But only book a call if you have a proven offer and a list.

Got it?


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