In general the tasks include:
- Obviously it is important to get up to speed on RAC concepts and develop a plan for what exactly it is you want to accomplish and/or prove. Deciding if you even need or can use RAC is always the first step.
- Setting up the hardware: servers, private network, shared storage, switches, etc.
- Configuring the O/S: system parameters, mounting storage, remote access, interconnect heartbeat parameters (hangcheck-timer), etc.
- Installing and configuring the software: clusterware, ASM (if desired), configuring init.ora's, creating instances, configuring tnsnames.ora's, listener.ora's, etc.
It's quite an initial project that requires teamwork between the DBA, server admin and network admin. I don't want to give the impression that it is unmanageable in complexity, because it is not, but it is time-consuming and requires detailed planning.
There are also several books that I consider invaluable, especially when starting with RAC for the first time. I own and recommend both of these: Oracle 10g Grid & Real Application Clusters by Michael Ault and Madhu Tumma and Oracle Real Application Clusters by Murali Vallath.
I hope this helps. Good luck to you.