Email marketing is the workhorse of the marketing world. It often works the hardest but doesn't get the attention that newer digital marketing tactics do.

Yet email marketing has the highest conversation rate out of digital and print marketing efforts, found the Direct Marketing Association. Plus, the average ROI for every dollar spent on email marketing is $44.25, according to ExactTarget.

If email marketing feels like your ol' marketing standby, freshen up your tactics and strategies this spring. It's worth investing in.

Below, you'll discover ways to gain more subscribers, craft better subject lines and even increase your click through rates.

Increase your email subscribers

A new study done by Adestra reviewed data from the last several years to find the tactics proven to grow your email list.

Offer discounts. Yes, as you guessed, most people hit "subscribe" on your newsletter for the discounts. The vast majority of individuals (85 percent) cited this as their main motivation.

Not all discounts are created equal. Any discount is better than none, but some may inspire more individuals to sign up. The biggest incentive? Percentage-off coupons, followed by free shipping, free trials and finally, dollar-off promotions.

Frame the offer differently. Only 41 percent of newsletter subscribers sign up to keep up with new products and information. While that's still a sizable chunk of your audience, reframe the offer to gain more subscribers. For example, say "Sign up to learn more data-driven ways to increase your email list." instead of "Stay up to date with our latest research." Always highlight the benefit to your consumer.

How to write better subject lines

You've grown your audience. Now, it's time to make sure they open your emails.

Get personal. Include the city or town name in the email subject line for the best boost. Adding their first or last name is your second best option.

Say what you mean. Email subject lines are not the place to test out your new joke or cute marketing slogan. With emails, your audience wants to know exactly what they're getting. A coupon? A newsletter? Say it like it is in your email subject line.

Keep it short. Over 55 percent of email is opened on a mobile device, found Litmus. Mobile devices have small screens, so you can fit fewer and fewer characters in your subject line. Under 50 characters is a good rule of thumb. Another way to think of it? Use 6-10 words in the subject line. These emails had the highest open rate of any others, found MarketingProfs.

Seal the deal: Increase click-through rates

You're so close! Get your reader to take the last step and actually click on the link you include in the email.

Include a clear call to action. It should be crystal-clear what you want your reader to do next. Complete their purchase? Download your latest e-book? Have a goal in mind before you begin writing your next marketing email. Then, make your CTA pop by using a button, larger font or different colors.

Link. Then link again. Add the same link into your email one, two or even three times. You want to give your reader multiple chances to click on your CTA.