Do you have suggestions as to how we should organize our documents?

A library of initial tags is added for each type of organization. You will want to refine this list to meet the organization's specific needs.  

Additional Tags

I suggest some very general tags, and then very specific that refine the general tags.

is an example of a general tag.  

Then create  as more specific tags.

Adding a date or fiscal year tag could be very useful when adding previous documents. Documents can be search by date - the date refers to the date the document was uploaded so this search is not useful for previous documents that are uploaded in bulk on the same date.   

This is one example only; there are many additional ways of organizing tags.