I am the admin of TFS 2015 Update 3. I would like to allow one power user create team projects permissions on a dedicated collection for his department. what is the best practices for this?
Thank you
To create team projects you must have the Create new projects permission set to Allow.
And this is for a dedicated collection, unless you explicitly add that power user to another team project collection admin group, otherwise he do not have corresponding permission to create team projects in that collection.
You could manage collection-level permissions through the web portal admin context or TFSSecurity command-line tool.