How to fix poor iPhone 4S battery?

Recently bought an iPhone 4S, which is currently running IOS 7 (the most recent update) and the battery life is terrible. After fully charging to 100% my battery life had dropped to 14% after 2 hours and 15 minutes of usage. Is there anyway to fix this?!

Yes, buy a new battery

Lower Screen Brightness:
1) go to settings
2) Go to Brightness
3) Turn off Auto Brightness
4) Slide the brightness slider to where you can see it comfortably

Disable Bluetooth:
1) Go to Settings
2) Go To General
3) Click on the Bluetooth Option and select Off

Turn off Wi-Fi unless in a Wi-Fi Area:
1) Go to Settings
2) Go to the Wi-Fi Option
3) Turn off Wi-Fi

Turn off Location Services
1) Go to Settings
2) Go to General
3) Go to Location Services
4) You can disable all location services; or just click off on those that you don't need location services for

Fetch Email Less Often:
1) Go to Settings
2) Go to Mail, Contacts, Calendar
3) Fetch New Data (Select either Manually or Hourly for the best battery life
4) Disable Push Email; you'll still receive your emails hourly/manually which ever you had selected but you don't need both Push/Fetch Enabled at the same time

Turn off Other Location Services:
1) Go to Settings
2) Go to Location Services
3) Go to System Services
4) Turn off Diagnostics & Usage, Location Based iAds