From Forum Nokia Wiki

Description

Although modern phone batteries are much more powerful than old batteries, there are still a lot of things that you can do in your application to make phone battery last longer.

Some important usability guideline are

• Minimize the use of vibrate function in your application as it’s a big drain on power.
  
• Don’t use the backlight and keypad tones if you don’t need them. By default keep them off in your application.
  
• Even if you are using backlight in application turn them off when application is in idle state or in background.
  
• Turn off bluetooth and wi-fi after its use, if you are using them in your application.
  
• Optimize application that running in the background continuously, it should take minimum resources as it will run continuously in background. Do not add GUI control in exe, if possible.
  
• Continuously use of GPRS will consume battery, so disconnect it whenever application is in background or phone is in idle state.
  
• Reduce brightness in your application.
  
• If application is playing audio/video media then keep default sound low, It does save huge battery life.
  
• Do not leave the camera on after use.
• Minimize the use of animated screensavers.
• Reduce the use of games.

Check also the Top 10 Energy Saving Tips under Forum Nokia Power Management pages.