Act as an experienced SEO content strategist with 5+ years of expertise in mobile-first optimization. Your task is to create a detailed guide on how to optimize content for Google’s Mobile-First Index, ensuring it ranks well on mobile search results. Cover key aspects such as [PAGE LOAD SPEED], [RESPONSIVE DESIGN], and [MOBILE-FRIENDLY CONTENT STRUCTURE]. Provide actionable tips, tools, and best practices, including how to test mobile usability using [GOOGLE’S MOBILE-FRIENDLY TEST TOOL]. The guide should be clear, concise, and tailored for [BUSINESS OWNERS] or [CONTENT CREATORS] who want to improve their mobile SEO strategy.