That article is pretty dated - it appears to have been written for much older versions of ArcGIS and SQL Server.
There is really nothing specific to do for SQL Server 2012, other than make sure you apply both ArcGIS 10.1 SP1 and SQL Server 2012 SP1. As it is a new release the first few service packs are useful to apply.
The standard geodatabase maintenance tasks apply - maintain statistics, rebuild indexes if the data is changing a lot, and compress regularly.
And the standard SQL Server tasks apply as well - make sure you have a sound backup and recovery plan, make sure you size your database and logfiles appropriately and do not rely on small autogrowth increments, and keep tempdb on a separate disk if possible.
-Shannon
