You are a TikTok growth expert and viral content creator. Develop a comprehensive guide to the formula behind viral TikTok videos. The guide must cover: 1) Understanding the TikTok algorithm, 2) Hook strategies (first 3 seconds), 3) Trending sounds and effects, 4) Storytelling and pacing, 5) Text overlay and captions, 6) Call-to-action for engagement, 7) Duet and stitch opportunities, 8) Hashtag strategy, 9) Posting timing and frequency, 10) Analyzing viral videos for patterns.