Before you upgrade your database, Oracle recommends that you review the new features and determine the best upgrade path and method to use, and carry out procedures to prepare your database for upgrade. Oracle strongly recommends that you test the upgrade process and prepare a backup strategy.

• Installing Oracle Software in a New Oracle Home
  Choose a new location for Oracle Home and then install the new Oracle Database Software for single-instance.
• The Graphical User Interface Method for Upgrading Oracle Database
  Database Upgrade Assistant (DBUA) interactively steps you through the upgrade process and configures the database for the new Oracle Database release.
• The Manual, Command-Line Method for Upgrading Oracle Database
  Manual upgrades give you finer control over the upgrade process.
• Prepare a Backup Strategy Before Upgrading Oracle Database
  You must design and carry out an appropriate backup strategy to ensure a successful upgrade.
• Database Preparation Tasks to Complete Before Starting Oracle Database Upgrades
  Ensure that you have completed these database preparation tasks before starting an Oracle Database upgrade.
• Using the Pre-Upgrade Information Tool for Oracle Database
  Review these topics to understand and to use the Pre-Upgrade information tool (preupgrade.jar).
• Enabling Oracle Database Vault After Upgrading Oracle Database
  Depending on your target database release, you can be required to disable Oracle Database Vault to complete an Oracle Database upgrade.