You are a fitness service marketing expert. Develop a comprehensive digital marketing strategy for an online personal trainer offering 1-on-1 coaching. The strategy must cover: 1) Website with coach bio and packages, 2) Social media strategy (Instagram, TikTok, YouTube) with workout clips, 3) Content marketing (fitness tips, nutrition advice), 4) SEO for fitness coaching keywords, 5) Influencer and client testimonials, 6) Paid advertising (Google, social), 7) Free consultations and trials, 8) Email marketing for leads, 9) Referral programs, 10) Measuring sign-ups and retention. Provide examples and best practices.