The LCD screen of a laptop is another huge power consumer. Adjust the brightness to the lowest level that you can tolerate.
Mute the speakers and try avoiding the use of multimedia softwares like Winamp, Media players etc to maximize the battery life.
Switch off the screensaver rather that using the screen saver.
Some OS's looks can consume more power. You can can turn it off from the Display properties option and choose themes that consumes less power.
Hibernate is better than Sleep - In the Stand By mode (or sleep mode), the computer turns of the hard drive and the display but memory remains active while the CPU slows down. This draws on the battery. In contrast, hibernation mode is better because the computer saves the current state and shuts itself down completely thus saving power.
While on the battery do not go for multiple tasks which consumes more power. Try to aviod resouce consuming apps.
Be familiar with the power option of your laptop. Go through the manual to know how to use it effectively.
Efficiency increases with regular hard drive maintenance. It is better to defragment your HD regularly as it reduces the load for data fetch.
Kill the Resource consuming apps which are not vital - Monitor your CPU resource usage
If you have setup any scheduled tasks then pause that while you are running on battery.
Unplug external devices after use as they are the biggest drainers of battery power.
Do not use the DVD/external drives while running on batteries.
Use sufficient RAM
Clean You Laptop regularly. Most dust particles on it can cause heating and this also consumed power.
Pack it up when you are not using batteries for quite some time, ensure that the charge is nearly 40 percent – remove the batteries and store it in a cool place.
Avoid leaving the laptop under direct sunlight or inside a closed car.
Strictly follow the battery recharge instruction given by the vendor. Some times partial discharge can cause problems.
Update software and drivers - Newer drivers and software are often designed to be more efficient.
Use the right adapter and make sure the battery is an original one or one with the correct specifications.