The title sums up this post pretty good. If you’ve got Android, more specifically a variant of Android that let’s you really tweak your settings, like  Cyanogenmod

Do you live in a place with 4G or did you just travel somewhere that has 4G? If so and you want your phone to actually last the whole day or two toggle the speed to 2G (it will actually toggle to not 4G which is often 3G). I find that if I don’t 4G drains my battery very quickly to where I worry about running out before getting home or to a hotel while travelling.

The trade-off is great if you’re just checking email and getting directions. When you want to stream video etc, just toggle the speed back on.

TODO: I’ll get picture of my quick-bar power settings so people can see what it looks like.

Tip 2: Want to use Wifi on a plane, toggle to Airplane mode, then toggle wifi back on. PS: Airplane mode also breaks many in program ads.