Wi-Fi Sleep Policy for better battery life

[cereal killer]

To save on battery make sure Wi-Fi goes to sleep when the screen is off. It's on by default and that will drain your battery very quickly when Wi-Fi is on but not in use (screen off).

To put it to sleep when the screen goes off:

Settings/Wi-Fi & Networks/ Wi-Fi Settings/Menu Key/Advanced Settings/Wi-Fi Sleep Policy's/ Off When Screen Is Off

 

[Szadzik]

WiFi uses less power than 3G so you are better off using it over 3G.

 

[jntdroid]

depends on the signal, but my wifi signal at home is super strong, so I leave it on non-stop with little battery drain, especially compared to 3G/4G... but again, my signal can reach my neighbor 2 doors down, so that probably helps...