Turning off 3G: If you don´t need
a fast data connection or the ability
to make video calls.
Turning off GPS: If you don´t
need you GPS for navigation or
geo-tagging of pictures or videos.
Turning off Bluetooth/IrDA: If
you don´t use a Bluetooth/IrDA
connection to a headset or any
other device.
Turning off WLAN scanning: If
you´re not currently looking for a
network.
Lower screen brightness/
timeout : Lower the screen
brightness and timeout.
Keep phone´s FW up to date:
FW updates could include better
battery management.
Close unused applications: Try
to have as few applications as
possible running, especially those
that use a WLAN or other network
connection.
Turn your phone off (or
change to "Offline" profile): If
you're in an area with no signal for
a long period of time.
Smartphones (N97, 5800XM etc.)
shouldn´t be turned off, because
this´ll take more battery than to
keep them on and change to
"Offline" profile.
Fully discharge from time to
time: There is no problem in
charging the battery often,
although you can improve your
battery indicator and the the
battery life, by discharging it every
15-20 charges in order recalibrate
it.