As you create a new SharePoint environment, you should consider how to organize its sites so that users can easily access what they need. Important questions that you should consider include:
What primary sites should be part of this environment?
What users should have access to each site and what are the user's needs and requirements?
What site templates will be used for each site?
Should site permissions be inherited or should they be unique for each site?
Will any sites share any components, such as content types or site columns?
Should the users see a different navigation interface at each site level, or should this be consistent throughout the hierarchy?
Should all sites in the hierarchy have the same look and feel, or will sites have their own color schemes and branding?
The answers for these questions may vary depending on the situation, so there's not really a set of rules on how to create a SharePoint site hierarchy. However, by taking the answers to the questions under consideration, you can determine the best approach to build around whatever situation you encounter.
When designing a SharePoint environment, draw out the site hierarchy's primary structure. You can use drawing tools, such as Microsoft Visio or something as simple as a sketch, to help you through the planning stage. From there, you can add information such as what templates to use, where you should define permissions, or where you should create content elements such as content types. ...