Three rules: First, never paste sensitive data (customer PII, financial records, trade secrets) into consumer AI tools (free ChatGPT, free Claude) — those conversations may be used for training. Second, use enterprise tiers (ChatGPT Enterprise, Claude for Enterprise, AWS Bedrock) that contractually guarantee your data is not used for training. Third, deploy AI on your own infrastructure when possible, keeping data within your network. Most enterprise AI providers offer SOC 2 compliance, data processing agreements, and the option to process data in specific regions. Read the terms of service — the free tier and the enterprise tier have very different data policies.