1. Dont always use the laptop with in A/C power. Switch off the adapter when the battery is fully charged (use it in battery mode) and switch on the adapter again when the battery level goes very low.
2. Keep your WIFI radio switch always off when not required.
3. Drain your battery completely at least twice a month. (Make the laptop get shutdown automatically when the battery is critically low, switch it on again and keep in BIOS page some time to drain it completely, till it gets switched off).
4. Unplug un-used devices connected via USB (like camera, joystick, external keyboard, mobile, external hard disk etc) when not required.
5. Avoid using StandBy/Sleep option rather use Hibernate option.
6. Use the right adapter to charge your laptop battery.
7. Temperature is a silent killer, temperature reduces the life of battery for all electronic devices (even mobile phones). Take measure to avoid over heating of your laptop. (People who play high graphics games rather keeping your laptop in a flat surface leave a gap between your laptop and the surface).
8. Use your LCD screen with low brightness as possible.
9. Do not pack the laptop in your carry case as soon as you shut down. Give a little time to cool.
10. Other less significant tips are, avoid using high graphics screen savers, reduce the start up process as much as possible, delete the unwanted back ground process, use power options in the operating system efficiently.

All the above tips, I have put with my own experience. Generally lithium ion batteries have a life of 2-3 years. People who use there laptops for more hours a day, take little care to have a good battery life. If no care the battery wont last more than a year.