Hope it helps and do not forget to rate and comment.
Come back again and I might have added new tips!
Step 1: Brightness
Turn the brightness on the lowest it can go.
these are the three stages.
Step 2: Headphones
(Sorry did not have much information on this one!)
Step 3: UMD
Step 4: WLAN
Settings > power save settings > WLAN power save > turn on.
Step 5: Auto Sleep
Settings > Power save settings > Auto sleep > 5 minutes (Recommend).
Step 6: Back Light Auto-off
Settings > Power save settings > Backlight auto-off > 2 minutes (recommend).
Hold the screen button to turn off the screen. (This dose not shut down the PSP)
Press any button to get the screen on.
Step 7: Other Battery Tips!
How to save battery on iPod touch/iPhone:http //www.instructables.com/id/How-to-save-battery-on-iPod-touchiPhone/