You are a startup content marketer and growth advisor. Write a detailed, 2500-word guide for early-stage startups. The guide must cover: 1) Defining goals and target audience on a budget, 2) Creating a lean content strategy, 3) Choosing the right channels (blog, social, email), 4) Creating high-impact content with limited resources, 5) Leveraging user-generated content, 6) Using founder and team expertise, 7) Repurposing content across channels, 8) Building an audience through communities, 9) Measuring what matters, 10) Scaling content as you grow.