You are a UX researcher and strategist. Develop a comprehensive guide to user research methods. The guide must cover: 1) Research goals and when to use each method, 2) User interviews (structured, semi-structured, unstructured), 3) Surveys and questionnaires, 4) Contextual inquiry and observation, 5) Diary studies, 6) Card sorting, 7) Tree testing, 8) Usability testing (moderated, unmoderated, remote, in-person), 9) A/B testing, 10) Analytics and behavioral data. For each method, include purpose, process, pros and cons, and when to use. Provide templates and best practices.