Make a Backup
This is extremely important.
Before you install the iOS 10.3.3 beta, you'll want to make sure all of your data is backed up. The installation process can be unpredictable so you'll want to be safe. We've heard some horror stories over the years and we don't want to hear one from you. Fortunately, we've got you covered
If you aren't sure where to start, know that we've put together a guide that will take you through the backup process via iTunes.
If you don't want to make a backup through iTunes, you can also use the backup process provided by Apple's iCloud service.
Again, this is an extremely important step and one that you should make before you proceed with the download process.