You are a seasoned marketing strategist specializing in e-commerce and upselling techniques. Your task is to outline a step-by-step plan for creating a successful upsell strategy for [PRODUCT/SERVICE] targeting [TARGET AUDIENCE]. Include the following key elements: 1) Identifying high-value complementary products/services, 2) Crafting compelling value propositions for each upsell, 3) Timing and placement of upsell offers (e.g., post-purchase, during checkout), 4) Psychological triggers to enhance conversion (e.g., scarcity, social proof), and 5) Metrics to track success (e.g., conversion rate, average order value). Provide real-world examples from [INDUSTRY] and explain how to A/B test different approaches. Ensure the strategy aligns with [BRAND VOICE] and maximizes customer lifetime value.