Every writer who’s worked in email marketing has been there. You’ve got a killer draft written. It’s got the right punchy headline, the content that’ll speak well to the reader, and a call to action that’s sure to get folks clicking through. But what do you choose for the subject line?

Email has to be one of the most popular methods of outreach these days, used by businesses of all sizes and types, keeping those relationships growing with their readers, hoping to be first on their mind when it comes time to make a purchase, subscribe to a service, or comb your content for answers. But it only works if the recipients read it. And the fate of that lies in the subject line.

What to write one that’s sure to get eyeballs on the rest of your content? Follow these ten tips to get started.

1. Brainstorm without constraint

The golden rule of brainstorming applies to subject line writing as well: At the beginning, there are no bad ideas. Write down everything that comes to mind, and refine it based on the principles below.

2. Look for keywords in your content

The goal of a subject line is to hint at the content to come once the recipient opens the email itself, so what better place to look for subject line inspiration than the email content itself? Look at your headline, look at your call to action, look at keywords that are repeated throughout your content. Chances are, these words - in some combination together - might make a good subject line indeed.

3. Try to keep things short

Depending on what email service they’re using and which device they’re checking it on, folks scanning email in their inbox may only see the first 40-70 characters in a subject line. If you don’t hook them early, your email is liable to end up in the trash. Shorter subject lines are better in that way, but even if the whole thought won’t fit, paying attention to the words that display “above the fold” can make all the difference in your open rate.

4. Don’t repeat information that exists elsewhere

The subject line is one of 3 pieces of information the recipient is scanning in their inbox, so don’t waste precious space repeating information that already appears in your email from name (which is hopefully your brand name) or the eyebrow text that acts as a sort of subheader to your subject line. With the email send name and eyebrow text taking care of a lot of familiarity and logistics, your subject line can be the most creative, energizing part of the triad.

5. Aim to generate curiosity

Remember that your subject line doesn’t need to be a complete representation of the email contents. It just needs to get people to open. Curiosity is a fantastic energy to be generating.

Some of the best ways to generate curiosity in a subject line include:

• Providing numbers: “3 Must-Have Items for Dog Owners, On Sale”

• Asking a question: “Would this look good in your house?”

• Intrigue: “You might’ve missed it last week”

6. Tie in an action

If you're promoting something in the email that requires an extra step from the recipient to access it, you might reference the action they need to take in the subject line as a means of generating some motivation on their part to learn more right away. “Register now: You won’t want to miss this event”

7. If the information is timely, say so

Nobody wants a high-pressure sales gimmick landing in their inbox, but if your promotion is timely, it can help to say so in the subject line as a means of generating urgency for the recipient deciding whether to open and read more. “Time is running out, taxes are due in a month” might get folks calling you quickly, for example.

8. Test multiple options

No matter which subject lines you choose, every email campaign sent is an opportunity to learn more about your audience, your messaging, and their likelihood to open a message. Most email platforms allow you to split your send audience into an A/B or even A/B/C test; wherein each group gets a different subject line. You’d keep all the other content the same, and when you look at the post-send reporting, you might learn something about which options worked best for your group. Do keep in mind that the smaller the list, the fewer variants you should use. You might not hit statistical significance, but bigger groups with clear preferences displayed in the data can teach you a lot.

9. Learn what works over time

By being intentional about your wording in subject lines, paying attention to your post-send reporting details, and running subject line tests routinely, you can get a feel for your audience over time. You’ll learn what works for them, what doesn’t, and get new ideas to try every send.

10. Never stop innovating

Knowing your audience is crucial. But we should also know that audiences change over time, whether that’s reflective of folks subscribing and unsubscribing over time, or just preferences and needs shifting as a natural evolution of time. It’s important to keep experimenting with new subject lines, to occasionally mix things up on recurring sends, and never assume you’ve reached peak performance.

Subject lines are just part of an email marketing content strategy that converts. Want help on this or any other part of your email marketing plan? Let’s chat.