The procedure is normally very simple: Don't do it.
With today's Oracle databases, there is little reason to do any tablespace reorganization. Many DBAs are in the habit of doing this activity to help performance by defragmenting the database. But Oracle does not suffer performance problems from a fragmented database. In fact, Locally Managed Tablespaces rely on fragmented database segments!
I would ask why you want to do a reorganization? What do you want to accomplish?
This was first published in July 2007