6. Selectively turn off/on radios
If you don't need Wi-Fi or Bluetooth or 3G, turn off the radios.
Settings > Wi-Fi
While you're here, disable Ask to Join Networks unless you use this feature often (just turn it on when you need to find a new network).
Settings > General > Cellular
Settings > Bluetooth
7. Airplane Mode
If you want to disable all the radios on your iPhone, the easiest way to do this is using Airplane Mode:
Settings > Airplane Mode
With Airplane Mode active, you can still selectively enable Wi-Fi and Bluetooth if you want.
8. Location, location, location!
iOS 5 bought with is a lot of Locations Services features, and iOS 6 has taken these to a new level. But the problem is that all of these features have a negative effect on battery life.
Settings > Privacy > Location Services
Either disable the whole lot, or selectively enable it for a specific set of apps. The more apps that can use Location Services, the more juice they'll use.
iOS 6 has some hidden tweaks too (hidden because you have to scroll to the bottom of the Locations Services screen and click on System Services to find them):
You can keep Location Based iAds and Setting Time Zone off permanently (your time is set by the local carrier automatically anyway).
Another revamped feature in iOS 6 is notifications. The new notification Center in iOS 5 gives you a greater overview of what's happening, but that comes at the cost of greater battery consumption.
Settings > Notifications
My advice here is two-fold. First, disable notification for any apps that you don't care about by clicking on the individual apps and switching off Notification Center:
Second, control which apps are visible on the Lock Screen by switching off View in Lock Screen. The more you have showing, the more often your screen will flick into life, draining precious battery power.
10. Disable diagnostics
Another potential battery-eating culprit in iOS 6 is Diagnostic & Usage data. Set this to Don't Send.
Settings > General > About > Diagnostics & Usage