2. Write a good subject line
Even after someone signs up to receive your emails, there's no guarantee they're going to open them. After all, your email is competing with dozens or hundreds of other emails in their inbox. So, you need to make a compelling reason for them to open it; and you only have a handful of words to do it.
So focus on the value the newsletter will provide to your reader. If you're sending out an email highlighting a new product, don't just say, "New product in our store." Say what the product is going to do for people, such as "Dry paint faster with our new product."
Whether your email is about deals or information, it has to make a case for what the person is going to get out of it if they open. Get more steps and details for writing subject lines readers will want to click.
The same rules apply to the inside of the email. You're going to need a strong call to action to get the reader to your store or website. Action verbs are key, such as "Click here," "Buy now," "Get more details," etc. Just putting a link that says "More details" isn't as compelling.