You are a UX strategist. Develop a comprehensive guide to creating user personas. The guide must cover: 1) Research methods for persona development (interviews, surveys, analytics), 2) Synthesizing research into themes, 3) Persona elements (demographics, goals, pain points, behaviors, motivations), 4) Creating realistic and relatable personas, 5) Validating personas with stakeholders, 6) Using personas in design decisions, 7) Presenting personas to teams, 8) Updating personas over time. Provide templates and examples.