that I just got from Jonathan Todres, who teaches in the NYU legal writing program: When you're editing someone else's work -- for instance, if you're a student who's required to edit a classmate's paper, or a law review editor editing a faculty member's work -- ask yourself, "What have I learned about my own paper from editing this other paper?"
As with all attempts to see the flaws in one's own work, this isn't easy to do well. But it's good to try. For instance, if you see some arguments that were meant to be rhetorically flowery but come across to the reader (you) as mere bloviation, ask yourself: Is there similar rhetoric in my article that I like but other readers may be turned off by? If the sarcasm in the article you're reading comes across as stridency or excessive combativeness, ask yourself whether your work suffers from the same problem. If you're seeing lots of redundancy or needless abstraction, look over your own work with an eye towards finding the same problems.
Ditto for the attorney who would edit his own work.
Every writer needs an editor. Too bad for those attorneys who are so proud of their work that they can't see the value in an extra set of trained eyes.
This sort of collaboration is facilitated by the use of standard proofreader's marks. That's what editors use.
Here's a pretty good listing of the marks:
http://www.espressographics.com/files/proofread.pdf
I have found that the unfamiliar person is most valuable, especially in long-running litigation. I recently finished litigating a case for 9 years, and after a few years, you begin to talk in short-hand with colleagues, your opponents and in depositions. You cannot fall into this in briefs. We went through two judges and three magistrates. Someone without any depth of knowledge has to be able to understand what you are saying.
The proof-reading marks really take me back. Back in the day, I worked in publishing as both a legal and literary editor. I also taught brief-writing and poetry at one time. I used those marks all the time. Heck, my mother was a professional proof-reader and used to mark up my school papers with them. But I haven't seen them for years, because revisions and editing are done primarily by the redline function of word-processing programs. Very rarely do I see handwritten proof-reading marks. I expect they are still used in publishing, though I wonder if it isn't done with a computer.