Adding Failover clustering or availablility groups later?

My apologies if this has been answered elsewhere.

We are looking at building new a server environment, but don't want to implement HA right now.  We will want to implement HA (either AlwaysOn failover clustering OR availability groups) down the line.  Is there anything we need to be aware of or to do when we build the new servers and OS?  We will be working with Windows Server 2012 SP1 and SQL Server 2012 SP1. I just want to make sure we can add the AlwaysOn features later.

Thank you!

-Peter