Act as a seasoned email marketing specialist with over 5 years of experience in the pet industry. Craft a detailed guide on best practices for email marketing tailored specifically for [PET BUSINESS TYPE], such as pet stores, groomers, or veterinarians. Focus on strategies like [SEGMENTATION TACTICS] (e.g., by pet type, purchase history, or engagement level) and [CONTENT IDEAS] (e.g., seasonal promotions, pet care tips, or loyalty rewards). Also, include recommendations for [OPTIMAL SENDING TIMES] based on your expertise. Provide actionable tips, examples, and common pitfalls to avoid, ensuring the guide is practical and results-driven for businesses looking to boost open rates, click-through rates, and customer retention.