What's the best way to do stuff on my phone that I don't want someone who goes through my phone and knows my password to know about?

If you want to keep certain activities or information private on your phone, here are some strategies you can use:

**Use Private Browsing Modes**: Most mobile browsers have a private or incognito mode that doesn’t save your browsing history or cache. Use this mode for sensitive searches.

**Lock Specific Apps**: Some apps allow you to set a password or biometric lock (like fingerprint or face recognition) for added security. Consider using an app lock feature if your device has it, or install a third-party app lock.

**Secure Messaging Apps**: Use messaging apps that encrypt conversations, such as Signal or Telegram, which offer secret chat features that prevent screenshots and keep messages from being stored on your device.

**Utilize File Vaults**: There are apps designed to secure private files, photos, and videos, often with password protection. Consider using tools like KeepSafe or similar apps to store sensitive content.

**Organize Your Home Screen**: Put apps that you want to keep private in folders, or move them to a second page out of general view. 

**Limit Notifications**: You can adjust notification settings so that sensitive information doesn’t appear when someone else looks at your screen.

**Use Two-Factor Authentication**: Secure personal accounts (email, social media, etc.) with two-factor authentication to make it harder for others to access your data.

**Clear Search Histories and Data Regularly**: Regularly delete your search histories and app data that might reveal your activities.

**Use a Password Manager**: Store passwords and sensitive information securely with a password manager that requires a separate password.

**Create a Guest Account**: If your phone allows it, set up a guest mode that limits access to your personal information and apps.

Remember that even with these measures, no method is entirely foolproof. Always be mindful of what you share and where you store personal information.