Granted, a high-quality product, a compelling offer and a robust email list are contributing factors, too. But if you truly want to increase your email open and click-through rates and to convert prospects into buyers, then you need to test your campaigns.

So, what should you test? Anything and everything. When you’re ready to get started, here are a few pointers.

Sender Line

Let’s start with the sender or “from” line. This is an often-overlooked part of the email. Your sender line should not read “noreply@xyzcocompany.com.” You may want to test inserting a person’s first name (Bob@xyzcocompany.com). The sender line should always include your business name, so that it’s easily identifiable in your subscribers’ inboxes.

Subject Line

You can test several elements here:

• Length — The debate continues over the optimal length of subject lines, but some email clients truncate them. To avoid being cut off, your best bet is to keep yours to 50 or fewer characters.
• Tone — Depending on your brand, you may want to test different tones in your subject lines (serious, humorous, urgent, etc.).
• Content — Test what resonates most with your subscribers: varying or excluding an offer amount (for example, $10 off any order; $10 off orders of $50 or more; 10% off sitewide, or merely “huge savings” sitewide), product or service price, and offer end/expiration date.

Preheader

The preheader is the small type that appears at the very top of any email that’s delivered in an HTML-based template.

Try not to repeat the subject line or headline here. Every spot in an email is valuable real estate, and you don’t want to waste it by being repetitive. Test hyperlinking to specific information elsewhere in your message and to different pages on your website. Test including an aspect of your offer that’s not mentioned elsewhere.

Headline

You can test using a headline only or a headline with a smaller subheadline. Test both the content and placement of your headline. Many subscribers preview their emails in their inboxes, so make sure the headline appears “above the fold” — in digital terms that means the top portion of your message, visible in the preview pane of the inbox.

Main Text

• Length — The rule of thumbs (given mobile users) is to keep it short. But test shorter vs. longer copy. While there are no hard-and-fast rules, trends show that word counts of less than 300 are more popular than those with double that.
• Type size — Test for readability and response rate. For emails read on desktops or laptops, 12-point text is preferable. Keep in mind, however, that many of your subscribers will be opening your messages on mobile devices. This calls for larger point sizes, roughly 17-22 points.
• Call to action — If you’re selling a product or service, test instructions such as “buy now” or “add to cart.” If it’s an educational or informational email, test “read more” vs. “more details” or other phrasing. Avoid “click here,” as it is not descriptive enough.

Design

• Images — Test size, placement and number of images.
• Layout — Test placement of headline, copy and calls to action.
• Color scheme — Experiment with background color and type color. Avoid reverse type (white type on black background), because it is typically hard to read.

Landing Pages

Do you take your subscribers directly to a product description? Or do you lead them to a category page or product gallery with myriad offerings? Test which strategy drives more traffic to your website.

Unsubscribe

To be CAN-SPAM compliant, your email must include the option to unsubscribe. How you present it, however, is open to testing.