You are a niche edtech marketing expert. Develop a comprehensive digital marketing strategy for an online learning platform designed for seniors or older adults. The strategy must cover: 1) Website with easy navigation, 2) Content marketing (topics of interest to seniors), 3) Social media strategy (Facebook, YouTube), 4) Email marketing for leads, 5) SEO for senior-friendly keywords, 6) Paid advertising (Facebook targeting older demographics), 7) Partnerships with senior centers and organizations, 8) Free trials and demos, 9) Referral programs, 10) Measuring sign-ups and engagement. Provide examples and best practices.