Notify users of their options for Google Apps training. Users accustomed to another application may find Google Apps unfamiliar. By making training available to them as early as possible, you can eliminate much of the anxiety that accompanies this sort of change.
Visit the Google Apps Deployment for Enterprise site to find resources like:
Quick reference sheets
Helpdesk training and resources
User Help Center
Google Apps professional training
Have users prepare exclusion folders if necessary
When you configure your migration, you can elect to exclude specific top-level folders. A top- level folder is any folder at the same level as the Inbox folder.
If there are messages that you or your users want to exclude from migration, you can have your users prepare exclusion folders prior to migration, locate those folders at the same level as their Inbox folders, and then move all relevant messages to those folders.
For the sake of simplicity, enforce a naming convention, like Excluded Mail. Then when you identify the folders you want to exclude from migration, you have a reliable method of specifying the correct folders for every user.
You specify excluded folders by entering a comma-separated list in Step 3 of the migration wizard.