Assuming you are on iOS 11, most of what you need to setup can be found under your main account settings; iCloud, and iTunes and App Store. You should also visit Accounts & Passwords (further down the list) to choose which email accounts and what features of each account will sync to each iPad.
There are other decisions to make about the use of iCloud Drive, iCloud Photo Library, iCloud Music Library, whether you sync your iBooks collections, and much more. It’s a good idea to set asside an hour and just browse the settings for all of Apples built in apps (Messages, Facetime, Photos, etc.), as well as the optional ones you may have downloaded.
Search for and read up on any of the services you don’t understand. Besides the user guide (downloadable in iBooks), and serching the web, there are some tutorials in the Apple Support app (downloadable in the App Store).
Finally, you may need to decide what thrid party apps should (or should not) sync. Examples of these might be a password app, thrid pary message app, a cloud service (Dropboxz0, or a browser (bookmark syncinc).
If you are not on iOS 11, most of these setting still apply, but they may be in different places.
iPad User Guide for iOS 11.2 by Apple Inc.
iPad User Guide for iOS 11.2 by Apple Inc. on iBooks
