How Take a screenshot on an iPhone/iPad/iPod Touch

1. Turn on Auto-Brightness

The iPod touch's built-in light sensor can be your ally in extending your iPod touch battery life. When Auto-Brightness is turned on, the sensor will automatically adjust the brightness of the screen based on how much light is nearby. This means that in brighter settings, the screen will be dimmer, allowing you to use ambient light to see the screen and reducing the mount of battery life needed to power the screen.
Find it in the Settings app -> Brightness & Wallpaper -> Slide Auto-Brightness to On

2. Reduce Screen Brightness

Instead of using auto-brightness, you can also set one brightness level no matter what environment you're in. In this case, use the Brightness slider. Needless to say, the brighter the screen, the more battery it requires. Keep the screen more dim to conserve more of your iPod touch battery life.
Find it in Settings -> Brightness & Wallpaper

3. Keep Wi-Fi Off

Unlike the iPhone, the iPod touch only connects to the Internet when there's a Wi-Fi hotspot nearby. Because of this, iPod touch batteries aren't usually drained by constantly trying to connect to networks. Some users may keep Wi-Fi turned on at all times in hopes that an open hotspot will appear, but drains your battery and only works well in some places. So, unless you’re using Wi-Fi right now, keep it turned off.
Find it in Settings -> Wi-Fi -> Move Slider to Off

4. Turn Off Location Services

While the iPod touch offers Location Services, it doesn't have a built-in GPS. Instead, the iPod touch's location services require Wi-Fi to work (and we just talked about Wi-Fi, right?). Still, using these location services, your touch can offer you an approximate location and walking or driving directions, among other features. But, since it and Wi-Fi need to be on simultaneously to work, if you’re not using Location Services immediately, and don’t plan to right away, turn them off and conserve your iPod touch battery life.
Find it in Settings -> Privacy -> Location Services -> Slide to Off

5. Turn Data Push Off

The iPod touch can regularly suck down email and other data or, for some kinds of accounts, have the data pushed out to it whenever new data becomes available. Of course, both features require the iPod to be connected to a network via Wi-Fi, something we know drains battery. When you add this second data feature, you draining even more battery power. So, unless you're waiting for a super-crucial email, turn Push off to extend your iPod touch battery life (though with Push off, you’ll need to set your email to check automatically or do it yourself).
Find it in Settings -> Mail, Contacts, Calendar -> Fetch New Data -> Move Slider to Off

6. Fetch Email Less Often

The less your iPod touch accesses a Wi-Fi network, the less battery it uses. So, reduce battery usage by setting it to check your email less often. Try checking every hour or, if you’re really serious about saving battery, manually. Manual checks means you’ll never just have email waiting for you, but you’ll also stave off the red battery icon.
Find it in Settings -> Mail, Contacts, Calendar -> Fetch New Data -> Tap on Your Preference

7. Auto-Lock Sooner

You can set your iPod touch to automatically go to sleep - a feature known as Auto-Lock - after a certain amount of time. The sooner it sleeps, the less power it uses for the screen, network access, and other draining features. Try setting Auto-Lock to 1 or 2 minutes to save the maximum juice.
Find it in Settings -> General -> Auto-Lock -> Tap on your preference

8. Turn off Equalizer

The iPod touch has a built-in Equalizer feature in its music player that dynamically adjusts the music it's playing to increase bass, decrease treble, etc. Because this adjustment happens on the fly, it requires extra battery power. Turn it off to conserve iPod touch battery life. Turning it off means you'll have a slightly modified listening experience - the battery savings might not be justified for the true audiophile - but for those hoarding battery life, it's a trade worth making.
Find it in Settings -> Music -> EQ -> Tap off

9. Do Less-Battery-Intensive Things

Not all ways to save battery life involve settings. Some of them involve the way you use your iPod touch. Things that require it to be on for long periods of time, or use a lot of system resources, suck the most battery. Of course, some of these things also make the iPod touch the most fun, like movies and games from the App Store. But if you need to conserve battery, limit your use of battery-intensive apps.

10. Buy an Extended Life Battery

If all othe methods fails, maybe you just need more battery. Accessory makers like Mophie and Kensington offer extended life batteries for the iPod touch (just make sure not to accidentally buy one designed for the iPhone - they look very similar). If you need so much battery life that none of these tips are enough, an extended life battery is your best bet. With one, you’ll get days more standby time and many hours more use.