Disable Location Services
Your iPhone is capable of sharing your location with any app you have on your iPhone. While this might be useful for apps like Apple Maps or Waze, not every app needs access to your location, especially not your exact location at all times.
This is why the NSA recommends ditching Location Services and only using it when necessary. It also recommends not bringing your iPhone to sensitive locations, which is a simple but useful tip.
If you want to turn off location services on your iPhone, go to Settings > Privacy & Security > Location Services and turn off Location Services at the top of your screen. If you feel like you need to use this feature, scroll down and select which apps will have access to your location.