How to improve HTC One X battery life?

Reduce display brightness
HTC One X big 4.7″ 720p HD Super LCD2 IPS display is the biggest battery life eater of all. By disable Automatic brightness and set it to the lowest level that you need will improve battery life a lot.

Remove unused widget
The more widget you have, the more battery life will be eaten especially those widgets that use data connection and auto sync based on schedule like HTC Weather. Therefore, only keep those widgets that you really need.

Poor signal decrease battery life
Phone will use more power to increase signal strength. Always make sure that your phone has a good signal reception. Switch to 2G if 3G connection signal is poor at your area.

Turn off 3G data connection, use Wi-Fi
Always gets connected with Wi-Fi when available. 3G data connection eats more battery compare to Wi-Fi connection. Turn off both of them when not needed.

Disable / reduce auto-sync
Data connection eats battery life. Disable or reduce background scheduled auto-sync applications like Gmail, Twitter. And reduce the frequency of auto-sync will also help to improve battery life too.

Turn off Bluetooth & GPS
If you don’t use Bluetooth or GPS, turn them off. Only turn on them when needed.

Disable unused bundle applications
You can freeze HTC bundle software like AMPed 2.0, deF!ND, Mobile TV, My SingTel, SingTel IDEAS and Starhub MUSIC if you don’t need them. Why? They are running as service even you are not using them at all.

Fully close application that not use
Letting lot of applications running at background actually increase battery usage because they still require CPU processing. So fully close those applications that not needed.