Before you initiate the iOS 12 beta download on your device make sure you write down or store all of your important login information.
First of all you'll need your Apple ID to get started with the beta process.
The iOS 12 beta process requires a developer account or an Apple ID so you'll want to track down your info (or the info of the person you're installing for) before you attempt to install it. If you don't have this information you won't be able to proceed.
Once you get the iOS 12 beta installed on your iPhone or iPad, there's a chance you'll be logged out of some of your apps and services. We've been logged out of first-party and third-party applications in the past.
If you haven't had to login to your accounts in awhile, you may have forgotten your login info. If you use a ton of apps on your device, tracking down this information could prove to be a huge pain. This is especially true if you rely on these apps and services to get through the day.
The last thing you want to be dealing with during an important day or work or school is tracking down your various logins because iOS 12 beta logged you out. Get it done ahead of time and you'll be off and running in no time.