Achieving a clean design involves several key practices. Firstly, use a simple and clear layout. Avoid cluttering the email with too much text or too many images. Secondly, make use of white space to create a sense of openness and clarity. Thirdly, choose a readable font size and style, and stick to a consistent color scheme that aligns with your brand. Lastly, make sure your call-to-action (CTA) buttons are prominent and easy to click.