Act as a senior SEO content strategist with 10+ years of experience in creating high-ranking pillar pages. Your task is to outline a comprehensive step-by-step guide for writing an SEO-friendly pillar page on [TOPIC]. Include the following sections: 1) Keyword Research (target [PRIMARY KEYWORD] and 3-5 [SECONDARY KEYWORDS]), 2) Content Structure (use [HEADER HIERARCHY] like H2, H3), 3) Internal Linking Strategy (link to [5-10 CLUSTER PAGES]), and 4) On-Page SEO Best Practices (optimize for [TARGET AUDIENCE]). Provide actionable tips for maintaining a balance between depth and readability, and suggest tools like [SEO TOOL] for optimization. End with a checklist for pre-publishing review.