HI,
Follow these steps :
**** Take a full backup of the Vcenter Database and all the other components database.
**** Take a snapshot of the DB and the VC server if they running on a VM.
1. Upgrade your Vcenter.
2. Using upgrade manager apply the patches to one host at a time ( put the host in maintenance mode and then patch it, moving the VMs off the host)
3. I am not sure if you are going to upgrade SRM ( please let me know ).
Let me know if you need any further information.