An Overview of the Active Directory Design Process
In this article, Dan outlines vital considerations when planning and designing an Active Directory implementation.
Dan covers the process end to end - from initial business decisions such as why you are undertaking the implementation, to high level Forest and Domain design considerations. Dan drills down into areas such as Sites and Domain Controller placement, OUs and administrative delegation, before rounding off with a discussion around how you can take better control of your new environment through the application of Group Policy.
You can read Dan's article here.