1. Turn down the screen brightness - mine is set around 25%. and turning off auto-brightness pon berkesan jugak.
2. Adjust your poll time to check for email less frequently. - i use Push for exchange mail, fetch for yahoo mail and gmail. set fetch period to hourly.
3. Turn off the WiFi. - this one is obvious aku rase. the longer u connect to wifi, lagi cepat la abis. handphone mane2 pon same. i seldom use wifi since im on unlimited data plan. hehe!
4. Turn on Auto-Lock for the screen. - mine is set for 1 minutes dan ianya amatttttt berkesan.
5. Turn off the Equalizer. - tried this too but doesnt see that much difference. oh well..try je lah :D
6. Pack more juice. - yg nie blum beli lagi. tgh usha Morphie Juice Pack. survey2 harga dlm RM 300++. maka K.I.V dulu. hehe!
7. Take advantage of the commute time. - dunno about this one. sbb my fren charge his iphone in his car one time and completely brick his iphone :( (this is a risk im sooooo NOT willing to take)
8. Kill the vibrate. - yeah guess so. lagipon vibrate die mcm geli2 je. u can hardly even notice it! set ring volume to MAX!
9. Turn off Bluetooth. - tak penah on pon since bukan bleh buat file transfer pakai bluetooth pon. /sigh/
10. Update the phone often. - yg ni mstilah wajib. i'll constantly update u guys if Apple released any update ( follow me on Twitter ok?) *wink wink*
p/s : Need any help on jailbreaking ur iPhone (or anything about iPhone, seriously), it'll my utmost pleasure to help ;D
Sources : [TestFreak]