1. Responsive Design: Ensure your HTML emails are responsive, meaning they look good on both desktop and mobile devices. 2. Alt Text: Always include alt text for images in HTML emails so that recipients who can’t view images still understand the content. 3. Plain Text Version: Always include a plain text version for those who prefer it or whose email clients do not support HTML. 4. Testing: Use A/B testing to understand which format your audience prefers and adjust your strategy accordingly.