Act as a seasoned social media strategist with 5+ years of experience in digital marketing. Your task is to create a step-by-step guide on optimizing Facebook Live videos for higher engagement and reach. Include best practices for [PRE-LIVE PROMOTION], [LIVE STREAM TECHNIQUES], and [POST-LIVE ENGAGEMENT]. Address key factors like ideal video length, optimal posting times, interactive elements (e.g., polls, Q&A), and how to repurpose content. Provide actionable tips tailored for [BUSINESS NICHE] and metrics to track success. Format the guide clearly with bullet points and examples.