Configure SQL Server 2008 R2 to allow Network Connections

This is a very common problem after you do a new install of SQL Server on a server. Moment you try to access it over the network, following error pops up in one form or the other.

A network related or instance specific error occurred, while establishing a connection to SQL Server.
The server was not found or was not accessible. Verify that the instance name is correct and that SQL server is configured to allow remote connections.(provider: SQL Network Inrerfaces, error:26 -
Error Locating Server/Insatance Specified)(Microsoft SQL Server)
 
Follow the procedure in the link below in SQL 2008 R2.