Generate a full detail guide for entrepreneurs on creating a Personal Knowledge Management (PKM) system. The guide should be a practical productivity system. It must include detailed sections on: 1. The 'Capture' Habit: Tools and techniques for capturing ideas and information on the go. 2. The 'Organize' Phase: A comparison of popular organizing methods like PARA or Zettelkasten. 3. Choosing Your Tools: A look at apps like Notion, Obsidian, and Evernote. 4. The 'Retrieve' Habit: How to build a system that allows you to find information when you need it. Please include a supportive disclaimer.