Go to Settings > Privacy > Location services.
Here you’ll find a whole load of apps that are using GPS to update your location. It’s useful for something like Find my iPhone, but the chances are there’s a whole load of other apps that don’t need it and are draining your battery.
Settings > Mail, Contacts, and Calendars > Fetch New Data > Manually
At the moment, your iPhone is checking to see if you have new updates for mail, calendars, and contacts and it’s taking a toll on the battery.
You’d be surprised how many people don’t know about this. Double tap the main button then swipe up to close them down. It will save battery, but this is contingent on your use of background app refresh (see point 10).
If you’re never using them again, then delete them: hold down till they wobble and press the cross.
Settings > General > Accessibility > Toggle Reduce Motion on.
This is the feature that make it look like apps are floating above the background when you move the phone. It looks pretty, but it drains battery.
Settings > Wallpapers & Brightness > Tone it down a bit. You can also do this by flicking up from the bottom of the screen.
And while you’re at it – toggle off auto-brightness.