I'd recommend the following general guidelines:
- Pick a reasonable block size for the database and try to use it throughout if it makes sense. That was make management easier down the road.
- Use automatic undo management.
- Use locally-managed tablespaces whenever you can -- even for SYSTEM.
- Use automatic segment space management.
- Make sure you know what characterset your database requires and do your best to understand the impact of choosing a characterset. Many times, this will be most evident when using the export and import tools.
- Understand how the storage is configured on your host and do your best to separate different file types (redo logs, data files, archived redo logs) from one another.
This was first published in April 2004