1. Set your Network Mode to GSM Mode when not using 3g.
When your running low on battery life, or you don't get a 3g connection in your area, improve your battery life by changing your network mode to GSM only. 3g is best for internet use and is the best way to go for voice as well, but GSM ain't that bad for voice. If I'm not planning on using the internet and I'm running low on battery, I'd shut 3g off. This will stop your phone from searching constantly for a 3g signal that might not even exist in your area or be spotty.

2. Change Your Screen Display Settings.
These Nokia handsets already have bright and beautiful screens. There's no need to keep the light set to the brightest possible setting when your trying to be battery consious. That will drain your battery fast! Then again, I don't like my screen dim and dull either. I set mine to the setting right below the highest. It keeps the screen bright and sharp, and does a lot to save on battery life.

Also, set your light time-out to something lower like 30 seconds. You'd be surprised at how much an extra 20 seconds at a time can drain your battery. Say you touch your phone 200 times throughout the day. Thats an extra 40 minutes your backlight is on if you keep at 60 seconds, as apposed to 40 seconds.

And when your on that very last bar, just suck it up and turn your brightness all the way down. It should add a good deal of time to the small amound of life you have left.

3. Don't Leave Applications Running When Unused.
Keeping applications open in the background when your not using them can be costly to your battery. A lot of times, new S60 owners don't know that if you don't properly close out of the application, it will just get minimized to the background. Hold down the Home/Menu button for 3 seconds to pull up your task manager.

4. Turn Off WLAN Scanning if your not using it.
If you don't turn this off, your phone will always be searching for a hotspot and waste battery life. It's just not necessary unless your near a known hotspot browsing the web.

5. Don't use your bluetooth headset if you absolutely don't have to.
Alot of people use bluetooth constantly, but this will really get your battery working. After the work day is over and you end up hitting the bars, leave your bluetooth in the car and do your best to conserve your E71 battery. It really sucks when you don't have a car charger.