1. Airplane mode :
It is the best way a user can make the most of this feature when in low-coverage areas or if you want to preserve battery life without powering down.
2.Turn off location-tracking apps :
Many apps like Google Maps,Twitter to your camera especially Facebook are tracking your location at all times. You can turn off Location Services completely Go to Setting >Privacy >Location Services ) or disable certain apps , one by one which are not important for you.
3. A Hard restart :
When your iPhone is running especially slow , you can go for a hard restart. Sometimes restarting your iPhone will flush out wonkiness and also free up space, you can also go for the restore factory setting , but you'll want to move all your data to the cloud ahead of time.
4. Update when you can :
Apple periodically awails updates to fix bugs and glitches, it could be a smart move -as long as the device supports the upgrade. Apple updates will tell you if devices (like iPhone 4S and higher one) can take the upgrade and it might just be the fix you need.
5. Turn off Fetch :
Some people want to keep the "Fetch" button on to retrieve emails and calendar updates automatically. Visit Setting >Mail, Contacts and Calendars > Fetch New data and make sure "Manually" is selected. This will increase the speed of your phone, saves battery life also and prevents from unnecessary updates. you can turn on when you want to update.
6. Background app refresh :
The Background app refresh is set to "On"in iOS 7 this feature lets apps run in the background while you multitask and continually refresh content when running on Wi-Fi or a cellular network. To disable this feature, visit Settings > General > Backgroud App Refresh . Here, you can turn off the entire function or just disable the apps you don't need to refresh on an automatic basis.
7. Hogging memory :
You may be surprised to see how many apps and services are running in real time, even when you are doing nothing . Visit Setting > General > Usage and check out which apps are hogging memory .
At last go ahead make sure you're running the latest version of iOS7 , just to be sure you have the latest security updates . You've probably collected dozens of apps over the years that you rarely or never use, and each one is taking up valuable space. Get rid of them .