Turn off GPS/Location Services
Speaking of GPS, you rarely need it. Unfortunately, turning GPS off and on isn't (as of this writing) anywhere near as easy as toggling Bluetooth and Wifi. There are degrees of GPS activation and deactivation, and killing it entirely can mean diving back through the full settings menus every time you want an app to know where you are. The less annoying option is to simply limit the number of apps that require location data. Chances are, this is a much longer list than you'd expect, since many programs that have no mapping component still want to find your position, to serve you location-based ads (or to sell location data to third parties). Find that list – go to Location under Android's settings or Privacy for OS – and turn the feature off for everything that has no business finding you.