The Fried Center Group

My last writing project went through so many small edits that I eventually lost track of which version was current. For my next one, I want a much cleaner revision process. I am considering an affordable writing service and plan to ask about changes before any work begins. For those who have worked with outside writers, how do you normally send feedback? Do you collect every change into one message, use comments in the document, or follow another method that keeps revisions simple?