Experian found that emojis in the subject line can increase open rates by 45%. But in B2B business or a more formal business, emojis may seem inappropriate.

Use language that is unique to you and complements your personality.

Studies show that personalised subject lines can increase open rates by 50%.

Numbers lend credibility to your message. Include a statistic from a survey, a time-saving figure, the discount percentage figure, or the number of steps in your how-to-guide.

It's getting harder to be noticed in people's inboxes. Yet, email is still the most effective channel to engage, convert, and retain potential customers.

• Consider using a question to add interest or promise to show how readers can do something. For example, "Jane, here's how to boost your home's value."

A Yesware study found that email subject lines between one and five words had the highest open rates. A Marketo study found subject lines with about 41 characters or seven words had the most engagement.