Act as a seasoned Google Ads specialist with 5+ years of experience in e-commerce marketing. Your task is to provide a step-by-step guide on optimizing a Google Shopping campaign for [PRODUCT CATEGORY] to maximize ROI. Include best practices for [BIDDING STRATEGY], [PRODUCT FEED OPTIMIZATION], and [AUDIENCE TARGETING]. Highlight common pitfalls to avoid, such as [MISCONFIGURATION EXAMPLE], and suggest advanced tactics like [ADVANCED STRATEGY]. Structure your response with clear action items, data-driven insights, and real-world examples tailored to [BUSINESS SIZE].