presuming that OS is installed and all the required OS patches are applied.

the high level steps includes ...

1. prepare file systems to store DB files (co-ordination with storage admins)
2. test the OS level fail over scenarios like NIC failure, HBA card failure etc (co-ordination with system engineers / network engineers)
3. if you are using cluster (active / passive) then test fail-over scenarios for the same (co-ordination with system engineers & cluster engineers)
4. install Oracle binaries and patch it as par your requirement
5. create DB

Thanks,