Don't be one of those people who post on Facebook asking for people to message you their phone numbers because you didn't back up your phone -- back up your iPhone, iPad or iPod Touch prior to pressing the install button foron Sept. 17.
You can use either iCloud or iTunes to back up your iOS device. Both choices have advantages and disadvantages, but at the end of the day having a backup of your device can prevent a lot of headaches (and potential heartache) should anything go wrong when updating to iOS 12.
Using Apple's iCloud service to back up your iOS device is the easier method. Each iCloud account is given 5GB of free storage for things like backups, so why not use it?
To force a backup of your iOS device using Apple's iCloud service, go to Settings > tap on your name > iCloud > iCloud Backup > Back up now.
Make sure you're connected to a Wi-Fi network and have a charger handy. You don't want to burn through your wireless data plan, and the backup process can chew through a lot of your battery in a short time.
Another way to back up your iOS device is to use iTunes. You'll need a computer with the latest version of iTunes installed and an Apple Lightning cable.
Connect your iOS device to the computer and unlock it. Enter your PIN code if prompted to approve a connection between the computer and device.
In iTunes, click on the small thumbnail of your device next to the Music/Movies drop-down menu.
With the Summary option selected on the left, you should see a screen full of details about your device. On that screen is also a Backups section. Leave iCloud selected, but select the Encrypt iPhone backup box. You'll be asked for a password that will be used to encrypt the backup. Whatever you do, do not lose or forget the password you enter -- without it, you can't restore your iOS device's backup should you need to.
With a password entered, click Back Up Now and let iTunes work. A few minutes later, you'll have an encrypted backup stored on your computer.
An encrypted backup will prevent you from having to enter account passwords for apps like email or Facebook when restoring a device, as opposed to iCloud backups that can be hit or miss.