Whether you're looking to build loyalty or achieve any other goal with your newsletter, the starting point will always be a quality database.
Forget about buying contact lists; it's a practice that can have legal c level executive list consequences and is also ineffective. Very few recipients will likely be interested in reading the message you send.
Create a simple subscription form and implement strategies such as a discount or gift in exchange for the subscription, for example, giving away a free ebook is a very effective practice.
A good strategy is to implement data collection strategies in your brand's other communication channels.
Some good options are:
Include a CTA that encourages subscription to your blog pages.
Set up pop-up forms on your website. Make sure they're not too intrusive. It's important to strategically choose the pages where they'll appear and to display them after the user has viewed a bit of your content.
Use your social media ads, sweepstakes, and links to include opt-in forms.
Take advantage of valuable content like free ebooks, exclusive promotions, premium resources, and exclusive content.
Create offline forms for your events, conferences, or physical stores.