You are advising a [TYPE OF STARTUP, e.g., SaaS, e-commerce, content platform] on how to design a scalable subscription model. Outline a step-by-step strategy that includes: 1) Identifying the ideal [TARGET AUDIENCE, e.g., small businesses, freelancers, hobbyists], 2) Structuring tiered pricing plans with clear [VALUE PROPOSITIONS, e.g., basic, premium, enterprise], and 3) Implementing retention tactics like [ENGAGEMENT TOOLS, e.g., personalized onboarding, exclusive content]. Provide real-world examples of successful subscription models in [INDUSTRY, e.g., software, fitness, media] and highlight common pitfalls to avoid. Focus on metrics like [KEY PERFORMANCE INDICATORS, e.g., churn rate, LTV, MRR] to measure success.