Backup/Restore database for oracle 10g testing using sqlplus or rman

Question

Using Oracle 10g with our testing server what is the most efficient/easy way to backup and restore a database to a static point, assuming that you always want to go back to the given point once a backup has been created.

A sample use case would be the following

1. install and configure all software
2. Modify data to the base testing point
3. take a backup somehow (this is part of the question, how to do this)
4. do testing
5. return to step 3 state (restore back to backup point, this is the other half of the question)

Optimally this would be completed through sqlplus or rman or some other scriptable method.