Summarize:

New iPod Touches will come with a partial charge, which will be enough to get you up and running. If you purchased your iPod Touch from someone else instead of a store, you may need to charge it before you can use it. When you first power on the iPod, you will be greeted by the "Hello" screen. Swipe this screen from left to right to begin the setup process. If your iPod is secondhand and you want to start the setup process from the beginning, tap Settings → General → Reset, and then tap "Erase All Content and Settings". The next time the iPod Touch is turned on, the initial setup assistant will begin. The first settings you will need to choose are your language and location. Choose your primary language, as this is what the iPod's interface will be displayed. If you travel a lot, choose your home country as your location, as this is what your iTunes store is based on. You will be asked to connect to a wireless network during the setup process so that the iPod can connect to Apple's servers. You will be provided a list of available networks. Choose yours and enter in the password. If you can't connect to a wireless network, you will need to plug your iPod into a computer and continue the setup process through iTunes. After you connect to a wireless network, you will be given the option to restore your settings from an old backup or set up your iPod as a new device. If you are transferring your settings from another device, select whether the backup is located on your computer or on iCloud. If you don't have a previous backup, tap the "Set Up as New iPod" button.  If you are restoring from an iCloud backup, it will be downloaded and installed automatically. If you are restoring from an iTunes backup, tap the button and then connect your iPod to your computer. Finish the backup restore process through the iTunes program. Your Apple ID is what you use to log in with all of your Apple devices. It gives you access to iCloud, and allows you to make purchases from the iTunes and App Stores. If you don't have an Apple ID yet, you can tap the button to create a new one. You can enable iCloud functionality for your iPod, which will allow you to backup your apps and settings to the cloud. This will allow you to restore your iPod quickly if something ever goes wrong. There are a variety of other benefits for using iCloud, including accessing documents stored in the cloud, re-downloading iTunes purchases, and using the iTunes Match service (if you signed up for it). Since iCloud is free, it is usually recommended that you enable it, even if you don't think you'll be using most of the features. Newer iPod Touches have Siri capability, which is the voice-command feature on iOS. You can choose whether or not you want to use it, but enabling it won't interfere with the normal functioning of the iPod.
Power it on. Start the Setup process. Choose your language and location. Connect to a wireless network. Decide between restoring an old backup or setting up the iPod as new. Log in with your Apple ID. Choose whether or not to use iCloud. Enable or disable Siri.