- iPhone Applicatons - If you have 8 screens of iPhone Apps, I would start with a at least 2 empty screens of Apps before upgrading. There is a new iPhone Spotlight screen that takes up the screen position to the left of the home screen.
- Music - I woud reduce the number of songs you have on the your device before upgrading. This would reduce the amount of time the upgrade takes.
- Camera Roll - First of all, make sure your camera roll photos are backed up. If you are a Windows user, you can use Picasa. If you disabled the camera wizard, remember to re-enable it and save your pictures. You might consider deleting your history of Camera Roll Photos from the past 2-3 years and starting new. This would be the perfect time to do so.
- Photos - I would remove some of the photo albums if you have too many. On some of my iPhones, iTunes re-optimized the photos which took many hours.
- Other iPhone Synch Applications - Make a list of other iPhone Synch applications you may have. These may include Google Calendar, Yahoo Calendar etc.
- Add Remove Programs - go to Add Remove programs and write down the versions of the following: Apple Mobile Devices Support, Apple Software Update, Bonjour, iTunes and QuickTime. This would be beneficial if you need to re-install iTunes and Apple Support asks you to remove these items. If another program you are using uses for example another version of Bonjour, you have a record of this in the event your other program stops working.
- Backup Plan - If you iPhone or iPod Touch does not upgrade, make sure you reserve plenty of time for a potential diasters recovery plan. For example, are you going to call Apple, try to upgrade on a Mac (if a Windows upgrade) or schedule an appointment with Apple. How long can you go without a phone? Is your IT guy or IT family member available to help you?
That all said, before you start the upgrade, for both Windows and Mac users, make sure you have installed all software updates!