As a seasoned data strategist, outline the top [NUMBER] most effective ways startups can leverage big data to drive [SPECIFIC BUSINESS GOAL, e.g., customer acquisition, operational efficiency]. For each method, provide a real-world example from a successful startup, detailing how they implemented it, the tools they used (e.g., [TOOL/PLATFORM]), and the measurable impact it had (e.g., [METRIC IMPROVEMENT]). Highlight common pitfalls to avoid and key considerations for startups with limited [RESOURCE CONSTRAINT, e.g., budget, technical expertise]. Structure the response for clarity and actionable insights.