have a look at your Battery Stats under Settings to see what is chewing the battery. The phone should easily make it through the day. After 8h and 8m use I have 70% battery left today. You can try:
1. Ensure power saving mode is on.
2. Screen is on auto brightness.
3. You can use a flip cover with the little window that prevents the whole screen lighting up for notifications.
4. GPS, WiFi and BlueTooth should make little difference if not used as they go into idle mode and I just leave them on.
5. Try turning down apps from syncing too often and often once an hour is fine.
6. 3G chews more power than 2G / GPRS so unless you really need the speed, then rather set the phone to use 2G / GPRS only.
7. I am carrying a small portable WiFi hotspot to consolidate my data usage for my tablet and phone. This could be saving me a bit of power as my 3G is not used whilst the WiFi is connected.