Reblogged from Basit's SQL Server Tips:
This article walks the user through installation of SQL Server 2012 on a Windows Server 2008 system using the SQL Server setup installation wizard. The installation process is simple, straight forward and is very similar to SQL Server 2008 / 2008 R2 setup. The procedure described is for a non-clustered server, and can be applied either to a default instance or a named instance.