Get Familiar with iOS 15.7.3 & Older iOS Updates
First and foremost you'll want to get familiar with iOS 15.7.3's changes before you start the installation process.
We've released a walkthrough that will hold your hand through the notable changes on board the latest version of iOS 15.
If you've fallen way behind on iOS updates, and you're running an older version of iOS, you'll want to get familiar with any updates you skipped before you install iOS 15.7.3.
Again, the features and fixes from software updates you skipped are baked into your version of Apple's software.
Our iOS 15 walkthrough will take you through the changes on board previous versions of iOS 15. We've also released a walkthrough that will take you through the biggest changes on board the most recent versions of iOS 14.