How to back up and prepare your old iPhone for sale or trade-in ahead of Apple's iPhone 6 launch

Backups

Before taking another step, you should ensure that you've backed up your data — there's no worse feeling than realizing your contacts, photos, or Angry Birds saves have disappeared into the ether. Most iPhone owners have likely enabled automatic backups via iCloud; If you aren't sure, you can check the status by navigating to Settings → iCloud → Storage & Backup.

If iCloud Backup is already enabled, look just below at the "Last Backup" timestamp. Since iPhones will only perform automatic backups when locked, plugged in, and connected to Wi-Fi, the latest backup could be as much as two weeks old, and you'll want to run a new one before proceeding by tapping "Back Up Now."

This week, Apple launched new, cheaper iCloud storage plans, so if your iPhone is too large to back up to a free 5-gigabyte account, you can add more space to ensure you won't lose any of your precious data.

Alternatively, users weary of uploading their data to the cloud can back up to their computer using iTunes. Connect your iPhone to your computer with the Lightning cable, then open iTunes — you can either sync the device, or open File → Devices → Back up to bring up the backup menu. To start a backup, right-click your iPhone and select Backup Now.

Data Destruction

Wiping your iPhone is fairly trivial. Once you've completed your backup, tap Settings → General → Reset, then tap "Erase All Content and Settings."

You'll be prompted to confirm that you really want to erase your device. Users who've upgraded to iOS 7 and enabled Find My iPhone will need to enter their Apple ID, thanks to iOS 7's anti-theft provisions — this will allow the phone to be removed from your account as part of the erasing process.

That's it. Once you've completed these steps, it's safe to sell off your old phone and get ready for your shiny new one.