Properly configure DNS
Properly configure /etc/hosts files
Properly configure SCAN
Properly configure SHARED storage (Preferably ASM - "raw" devices) - make sure you partition the disk devices to "skip" the first 1MB of the device)
BEFORE installation, confirm grid-owner and oracle-rdbms-owner can read AND write to these shared devices from ALL nodes. Permissions must be set to <grid-owner:<grid+oracle shared group> (grid:oinstall where oracle is also in the oinstall group)
Properly configure ssh password-less connections for both GRID-owner AND oracle-rdbms-owner.
IP addresses required
3 SCAN addresses that point to myhost-scan.mydomain.tld in a round-robin fashion
1 public IP address
1 virtual IP address
1 interconnect IP address should be iin /etc/hosts ONLY - Non-routable and not reachable via the public interface. DO NOT use CROSSOVER cable.
Interconnect should be on a DEDICATED INTERCONNECT switch.
As for the SHARED storage, the LUNS/Devices can be "carved" out on your SAN by your SAN admin. MAKE SURE that ALL devices in a given diskgroup are EQUAL size. (ie - DATA000=250GB/each, DATA001 500GB/each etc)
The installation guide gives a lot of directions on PRE-REQUISITES. Follow them. And remember, since you are new to this, you may install this several times before you get it the way you need it to be. Even installing MANY RAC clusters on multiple platforms, I still install it 2-3 times. Generally because the SA has forgotten some pre-req step.