Act as a seasoned sales email strategist with 10+ years of experience crafting high-converting subject lines. Your task is to generate [NUMBER] best practices for writing compelling sales email subject lines tailored to [INDUSTRY] that [GOAL, e.g., 'increase open rates by 30%']. Include these elements: 1) Personalization techniques (e.g., using [NAME] or [COMPANY]), 2) Urgency and scarcity tactics (e.g., 'Limited-time offer'), 3) Curiosity-driven hooks (e.g., 'The secret to [BENEFIT]'), and 4) A/B testing frameworks. Provide [EXAMPLES] of winning subject lines and explain why they work. Format as a numbered list with actionable tips.