What kind of feedback do you all focus on? Any good resources I could check out to give better feedback?
* Turn on Suggest Changes so they can reject or ask questions more easily
* ASK THEM what sort of feedback they want: "Do you want feedback on grammar/wording, overall content and structure, or both?"
* If they want grammar/wording feedback only, I'll do a quick skim and correct some phrases
* If they want content/structure feedback, I'll provide that in a few comments throughout the doc
* If they want both, I'll do both
If you want to keep your friends, don't make more than 3-4 grammar corrections per page or so of content unless they ask for that feedback.
I also write a blog and the above is the type of feedback that I like to get. I find that experienced writers will often ask for feedback in the form of "tear it apart" (any and all feedback) or "just let me know if this makes sense" (content and structure).
> What kind of feedback do you all focus on?
It depends. I usually help a friend with this, but I do mostly style correction and typos. When I'm pointing a thing I usually explain why that correction is necessary (unless is something trivial).