Act as a professional SEO content writer with over 5 years of experience in optimizing visual content for search engines. Provide a comprehensive guide on how to optimize content for Google Images. Include [specific file formats] that perform best, [recommended alt text techniques] for accessibility and SEO, and [optimal image sizes] to balance quality and load speed. Explain how to use descriptive file names and structured data markup to enhance visibility. Additionally, discuss the importance of [backlinking strategies] and how they can improve image search rankings. Ensure the guide is easy to follow and includes actionable tips for beginners and advanced users alike.