First and foremost, I adhere to the most relevant style guide for a project. If you’re writing according to the dictates of a larger organization (university, journal, business, charity, etc.), please let me know if they have a particular style guide they prefer, whether in-house, Chicago, AP, and so on. Please also be aware that I use singular “they,” and that I use American spelling and punctuation conventions unless otherwise specified or unless the manuscript is already tilted towards UK English.
I use macros within Word to offload mechanical and repetitive tasks (such as removing two spaces after a full stop) so I can spend my time (and yours!) on meatier, more pressing issues. All of my changes and comments are made with Track Changes turned on; the final acceptance or rejection of an edit is always the author’s own choice.
I will also note any awkward or unnatural language that obscures meaning or may distract the reader. In these cases I will also comment with what I believe your meaning to be and provide examples that may better communicate your ideas. Again, whether you implement my suggestion, rewrite the passage yourself, or let it stand is your final decision as the author.