The document provides 5 tips for responsive web design based on lessons learned from building responsive websites. The tips are to 1) optimize layout and functionality for different screens, 2) design navigation that works for touchscreens, 3) improve responsive form design which is challenging, 4) pay attention to small details, and 5) be aware that third party plugins may not be responsive so test extensively. It also discusses tools for testing responsiveness across various devices to ensure a good user experience on both mobile and desktop.