Website testing, while seemingly straightforward, is complex due to the intricate nature of modern web applications and the pressure to deliver quickly in agile environments. Common mistakes in website testing include overlooking responsiveness across various devices, neglecting accessibility standards, and failing to properly configure the staging environment. The importance of cross-browser testing and ensuring page load speed are often underestimated, yet crucial for SEO and user experience. Testers frequently forget about the significance of clickable company logos, well-defined web element IDs, and the necessity of load testing under heavy traffic conditions. Security testing is paramount, especially in safeguarding user data and SSL certificate validation. Automation tools like Selenium are invaluable, but testers should avoid over-reliance on them and should integrate them with other tools for better scalability and reporting. Proper planning, testing usability with the right participants, and using analytics to understand user interactions are essential to avoid common pitfalls. Overall, embracing a balanced approach between manual and automated testing, while learning from past mistakes, can significantly enhance the reliability and performance of web applications.