Act as a seasoned digital marketing specialist with 5+ years of experience in Google Shopping campaigns. Your task is to provide a detailed, step-by-step guide on optimizing Google Shopping ads for [PRODUCT CATEGORY] to maximize [METRIC, e.g., ROAS, CTR, or conversions]. Include best practices for [KEY AREA, e.g., product feed optimization, bidding strategies, or audience targeting], and highlight common pitfalls to avoid. Use real-world examples and data-driven insights to support your recommendations. Tailor your advice for [BUSINESS SIZE, e.g., small businesses, mid-market, or enterprise] to ensure relevance.