You are a UX designer. Develop a comprehensive guide to first-time user experience. The guide must cover: 1) Goals of FTUE (immediate value, reduce drop-off), 2) Welcome screens, 3) Account creation simplification, 4) Permissions and notifications (when to ask), 5) Initial data and setup, 6) Highlighting key features, 7) Sample content, 8) Celebrating first success, 9) Examples, 10) Measuring FTUE success. Provide design patterns.