The Single Most Important Rule in Copywriting

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Copywriting is such a broad topic that trying to pick out one rule or aspect as the most important would be akin to trying to pick out the most important ingredient in a complex dish.

Depending on which chef you talk to, you are bound to get many candidates for most important ingredient that a gourmet world dish must have. And the same can be said about copywriting.

So many parts come together to make winning copy that it would be hard to settle on one all-important rule that makes it all work.

So we’re going to go for one that looks away from the work itself towards the all-important reader.

What’s the most important thing about winning copy? The person reading it. Converting them is the end all and be all of copywriting.

And nothing gives your copy more impact on a reader than the rule of one.

What Is the Rule of One?

The rule of one is one of the foundational tenets of copywriting and states that whatever copy you write should focus on: one big idea, one reader, one promise, and one call to action.

One Big Idea

This is the central core of your message. It is the one thing your entire sales message is built around and without which everything falls apart or becomes generic.

It is also one of the hardest things to get right when writing copy.

When you sit to write, you can start searching for your big idea by writing down a list of all the major benefits your product or service provides. And then pick out one that best addresses the reason why you know people are will to do business with you.

The truth is that all the many reasons why people want what you have can be boiled down to one strong reason that drives the purchase decision. You want to zero in on that. Focusing on anything extra will simply dilute the strength of your message and distract your reader.

One Reader

Many would-be copywriters fall into the trap of thinking they have to sell to everybody in order to write successful copy. And this stands to reason, after all the wider you cast your net the more likely you are to reign in something, right?

And so they write to target everybody and their best friend.

And then nothing happens. Crickets. No bite, no sales, nothing. Their copy doesn’t sell.

The truth is that good copy should be and feel like a one on one conversation. It should only be general enough to appeal to as many people who qualify as your one ideal buyer, yet specific enough to exclude pretty much everyone else.

Focus on one reader or ideal customer to increase your chances of being heard by the right people. If you try to talk to everybody at once, the chances are high that nobody is hearing you.

One Promise

There should be one bold promise you can offer your target customer for doing business with you. And that promise should be intimately tied to the outcome that your audience is looking for from your product.

For example, a clothing brand may promise its target customer with a something like: Become the best dressed guy in the room.

Your promise should go beyond your products to address the outcome you know your audience is most excited about.

One Call to Action

Your page should have a single goal. Only one. It is bad form and practice to ask readers to buy your product and sign for your email list as well in the same message, for example. Choose one, and then request the action as many times as you deem necessary throughout the sales message.

Serving up more than one call to action only serves to confuse your readers and make them less likely to take any action at all.


Learning to write great copy takes time and patience. So much practice. And don’t forget the rule of one while you’re at it.