A good newsletter banner is a balance of clean design and clear messaging. You can use any design tool, like Canva for example, or your own design software that you might commonly use for other design activities. Email marketing solutions like HubSpot or Substack also have their own integrated tools for curating the look of your email and host a number of customizable newsletter header designs.
Choose a design that aligns with your brand aesthetics, then add your logo, a suitable title, and any other relevant text or image. Make sure it’s visually appealing but not overly cluttered.