If your hospital’s email marketing could use some help, you’re not alone.

With so many digital marketing tools at your disposal these days, email marketing is still one of your best bets. But even if you’ve got a great email list in house, there are many factors that could be influencing your conversion rates.  Everything from the subject lines you choose to the images you use to when you schedule your blasts to where you place your call-to-action and how it looks has an impact on how far leads get in the conversion process.

To make matters worse, every organization’s audience is different. The best email practices for another hospital or healthcare provider may not be manifesting the best possible results, and they could even be lowering your conversions without you even knowing it.

Fortunately, there’s an easy way to determine what works best for YOUR audience. Almost every major email marketing tool supports some form of A/B testing, which allows you to create multiple versions of the same email and send them to randomly-selected segments of your mailing list. But running tests willy-nilly won’t help you improve your bottom line. For that, you’ll need a detailed plan with the elements you plan to test, the metrics you’re using to test them, and the baseline you’re measuring the results against.

What you should test

Some tests, like subject lines and sender names, don’t require much extra work at all. Others may take a little more effort but could have surprising results. Here are some of the things you can be testing:

Your call-to-action

Do more recipients click on textual or graphical CTAs? Should you place it at the top? Bottom? On the side? Colorful images catch the eye, but text links fit your copy like a glove. Since the primary goal is for people to click on these links, finding out which ones work best could have the biggest impact on your conversion rate.

Your content

What content is most popular in your newsletters? Give different pieces a chance in the spotlight at the top of your email and see which performs best.

Your sending time

Should you send your emails first thing in the morning? At night? Do certain types of content do better earlier or later in the week? If your email list isn’t huge, you may have to run this test a number of times over the course of a month to establish a pattern, though that’s true of other tests as well.

What you should measure

If you’re only paying attention to open rates and click rates, you’re not getting the whole picture. By dividing your click rate by your open rate, you can determine how the subject and the body of a given message are working in tandem. If an awesome subject line test leads to more opens but your click-to-open rate doesn’t go up comparably, you know that the body of your message didn’t live up to the expectations set by the subject line and you can focus your efforts accordingly to bring them in line with each other.

It’s important to set baselines for your testing so you can tell if changes are significant or just statistical noise. Factors like sample size will be important to keep in mind as well, and you may have to run some tests numerous times to extract meaningful data. You should also create a regular testing schedule, because what’s true now may not be the case a year or two down the road.