This document provides tips for building popular open source projects. It discusses the importance of critical mass and treating an open source project like a product to market. Key recommendations include giving the project a short, unique, and pronounceable name; providing an easy to understand synopsis; using an open source license; making the project easy to set up and use; documenting details thoroughly; and promoting the project through various media and community engagement. Fostering a positive environment where contributors feel respected and appreciated is also emphasized.