Originally posted by candychic125 at How to edit and comment effectively

I wanted to post this first because I thought it was decent advice, but secondly because I think that not enough editing goes around. People are coming out of the woodwork to ask me to help them edit. Not enough people provide useful feedback to writers, and it shows, people are starving for it. This makes a good point for my first advice-in-my-gallery posts.

Additionally, this sort of info translates into comments. You don't have to do a great big long line by line editing job to provide feedback. When you leave a comment, you can do any of the above.

One helpful addition, I think, is that if you are going to focus on pointing out issues the author has, you might want to stick to Three Big Things. Three things that they need to address (not three typos, but areas). More than that and you just might overburden them.