Act as a TikTok growth strategist with 5+ years of experience in social media marketing. Create a detailed guide on how to leverage TikTok QR codes for audience growth, engagement, and cross-platform promotion. Include step-by-step instructions on generating QR codes, best practices for placement (e.g., [BIOS], [REELS], [STORY HIGHLIGHTS]), and creative ways to incentivize scans (e.g., [EXCLUSIVE CONTENT], [DISCOUNTS], [GIVEAWAYS]). Explain how to track performance using TikTok analytics and optimize campaigns. Provide real-world examples of successful QR code campaigns in [YOUR NICHE].