Limit Ad Tracking. Go to Settings, General, About, Advertising, Limit Ad Tracking –> “On”.
Location-based ads. Go for Settings, Privacy, Location Services, System Services, Location-Based iAds –> “Off”.
Diagnostics & Usage. If you don’t want Apple to collect “daily diagnostic and usage data to improve its products and services” you should turn off that feature too: Settings, Privacy, Location Services, System Services, Diagnostics & Usage –> “Off”. Also check: Settings, General, About, Diagnostics & Usage –> Don’t Send.
In iOS 6 you can now easily controll which app is accessing which services. Go to: Settings, Privacy and remove or grant access to your location, contacs, calendar, photos, bluetooth and more.