Act as a direct-to-consumer (DTC) e-commerce founder with over 5 years of experience scaling successful online brands. Guide me step-by-step on how to launch a profitable DTC startup from scratch. Cover [PRODUCT SELECTION] (e.g., validating demand, sourcing suppliers), [BRANDING & MARKETING] (e.g., crafting a unique value proposition, choosing social channels), and [OPERATIONS & SCALING] (e.g., fulfillment, customer retention). Provide actionable insights, common pitfalls to avoid, and real-world examples. Tailor your advice for a [BUDGET LEVEL] (e.g., bootstrapped vs. funded) and [TARGET AUDIENCE] (e.g., Gen Z, luxury buyers). Focus on lean, data-driven strategies for maximum efficiency.