Effective marketing, whether it's digital or offline, boils down to this: find an audience, figure out what they need or want, and then deliver it. There's no doubt that email is one of the best mediums to help you do that! Here's where most marketing newbies go wrong. It isn't always about selling your audience on a product. In fact, that isn't at all where you want to start.
You want to start by building a relationship with your readers. You want them to get to know you (or get to know you again if you've slipped in your email marketing). You want to help them by sharing valuable knowledge for free so they start to like you and trust you. Only then will you be able to make an offer and have them pull out their wallet to buy it.
Pay attention to your website stats. Programs like Google Analytics can give you a lot of information of where your readers came from, what page they landed on, and where they were on your site when they joined your list. That data along with demographic information will tell you a lot about your audience.
As you start to email your readers, they will reply and get back in touch with you. Pay attention to what they're saying. And don't forget to read between the lines. Let's say you're in the parenting niche and you noticed that some of your readers are asking for suggestions on being a more present and patient parent. They complain about being short tempered and freaking out about the little things when the real issue may be that they are distracted by their phones and missing important cues from their littles.
Dig deep and see what you can learn about your market. Sometimes what they tell you they want isn't the real issue. On the flip side, it can be helpful to ask them for suggestions. Keep the questions open ended if you want the best possible answers.
Or consider having your readers fill out a simple survey. It's quick and easy to do with Google forms or Survey Monkey. Doing so will allow you to collect good data about your current audience and also give your readers a chance to interact. Having them contribute builds a sense of community, even via email.
Be sure to also go back and look at the past emails you've sent. Pay attention to open rates, click through rates, and unsubscribes. If a large percentage of readers opened the emails, that's a good indication they were interested in the topic. If they clicked a link to additional content, that's even better. If, on the other hand, you got a lot of unsubscribes, that might be an indication that either the topic was wrong, or your language and overall message didn't click with your audience.
Use all the data and information you collect to learn more about your target audience and connect with them on a deeper level. The more you know about your subscribers, the more effective your marketing will be.