I suggest you look for documentation on the Optimal Flexible Architecture (OFA). In addition, the Oracle DBA Handbook has a section devoted to your question.

Here are some ideas:

1. Put your control files on different disks if possible.
2. Put your redo log groups on different disks.
3. Separate your data and your indexes on different disks.

Points 1 and 2 support easier recovery. Point 3 helps performance by distributing I/O over different devices.

Good luck.