If you are using KM (Knowledge Management) and/or WPC (Web Page Composer) in your Enterprise Portal, and you are planning to upgrade, this information is important for you before starting the upgrade.
Take a look at this SAP note - 1687484 - KMC configuration - Upgrade prerequisites and make sure to back up the existing KMC configuration data (use Note 1000150 - Backup of KMC configuration) prior to the upgrade.
In addition, the information in the following SAP notes can help with the migration phase:
WPC (Web Page Composer)
If you are also using Web Page Composer take a look at Note 1371703 - WPC for SAP NetWeaver 7.3 - Upgrade Information. To learn more about WPC visit here.
The upgrade guides (official documentation) contain special preparation and follow up section for KM and WPC. Make sure to follow those steps.