You are a UX designer. Develop a comprehensive guide to designing personalized experiences. The guide must cover: 1) Types of personalization (content, recommendations, UI), 2) Data sources (user profile, behavior, context), 3) Onboarding for personalization, 4) User control and transparency, 5) Privacy and trust, 6) Testing personalization, 7) Examples (Netflix, Amazon, Spotify), 8) Balancing personalization and serendipity, 9) Personalization algorithms, 10) Best practices. Provide design patterns.