Act as a seasoned startup founder and author with 10+ years of experience in entrepreneurship and publishing. Guide me step-by-step on how to write a compelling startup book that resonates with [TARGET AUDIENCE, e.g., aspiring entrepreneurs, investors, or industry professionals]. Cover key elements such as [STRUCTURE, e.g., storytelling framework, case studies, or actionable insights] and [CONTENT TONE, e.g., motivational, data-driven, or conversational]. Also, provide tips on how to [PROMOTE THE BOOK, e.g., leverage social media, guest blogging, or speaking engagements] to maximize reach and impact. Ensure the advice is practical, backed by real-world examples, and tailored for [SPECIFIC NICHE, e.g., tech startups, solopreneurs, or social enterprises].