1. Copy datafiles to another mountpoint.
2. Copy init.ora file to $ORACLE_HOME with user oratest or oraprod
3. Generate the cloning script with RESETLOGS option and the new database name.
4. Made new entry into /etc/oratab with the new database name.
5. clone the database
6. alter database open resetlogs
7. add temp file into temp tablespace
8. from oracle 10g home bin directory run dbua
9. Preserve current db settings.
10.  To check the status of the upgrade run the following query:

select comp_name, status, version from dba_registry;

11. Check all the components. Compare to the original database components and make sure that all options that are ON are upgraded accordingly.