Upgrade from CRM 4.0 with SRM 3.0 to CRM 7.0 EhP3

Hi everyone, I'm looking for guidance for an upgrade from CRM 4.0 ABAP with SRM 3.0 on RHEL 5.3 and Oracle 10.2 to CRM 7.0 EhP3 on RHEL 6 and Oracle 11.2.  I want to know which steps to take from starting the upgrade, in which step should I upgrade the database and any additional tip that anyone could provide with prior experiences.

Thanks in advance!

Jesus Rodriguez