What you do is you create a new project that consist of your company standards and what have you and saveas as a .rvt file.
This option is available when you do a saveas. Go to File and click saveas. And when you want to add more to this template in the future just go to File and click Transfer Project Standard.
There are a lot of discussion on this topic , so I recommend you a little search and I guaranty you'll be a much better Revit guy.
Thanks! This is a great solution... one point of interest, it's called "Blank Leader", not "Null Leader" (easier to find in the family tree when searching by the correct name). Also, is there a way to change the line weight of this type without affecting the line weights of all other leaders in the project?