Making sure you do not lose everything
A phone that is lost, stolen or broken should cost you the phone and nothing else.
On your phone
The three that matter
- Contacts: Settings, Google, Settings for Google apps, Google Contacts sync. Turn it on. Contacts saved to the SIM or to the phone itself do not sync, so move them to your Google account.
- Photos: install Google Photos and turn on Backup. Choose Storage saver unless you have a reason not to.
- The phone itself: Settings, System, Backup. This covers app data, settings, SMS and call history.
Then check it worked
- Open contacts.google.com on any computer and see whether your contacts are there.
- Do the same with photos.google.com.
- A backup you have never verified is not a backup.