iPhone users know how to close an open app: simply press the Home button, right? Nope. Sure, that tucks it away out of sight, but in most cases it's still running in the background — and could be one of the main reasons your iPhone battery is draining so quickly. For example, if you close a GPS navigation app, iPhone thinks you still want it running -- so you'll hear turn-by-turn directions. Ditto for playing music and then minimizing it to read your email, browse the web or look at photos.

Instead, to properly close your open iPhone apps and save on battery life, double-tap the Home button and you'll see a multitasking bar appear at the bottom of the screen. Now press and hold an open (but minimized) app and all the icons will start jiggling. Tap the small red "minus" tab to close down the app properly.