Here it is, in front of you... a document... a wall of text, you just spend countless hours writing it. If it is an important one - you hand it over to a colleague to check and put suggestions. You get it back and it is a mess, it is worst than it was, you use your initial version, and both of you are frustrated.
Help (only) when needed
Quite often people help right away as they see some issue. If you weren't asked for help be mindful, especially if this is someone that you don't know and you just stumbled upon someone's text. You might look arrogant otherwise, even with the best intentions.
No less important is to wait for the author to finish a particular part of the text, as often suggesting something that is Work-In-Progress can lead to distractions for the author - personally, I hate as comments and suggestion pops out when I still work on this document (or at least part of it).
Have one person helping
I recently had a situation on an important postmortem document that was peer-reviewed by 2 people, one after another (in between I applied fixes). However after the second review, I was getting opposite suggestions than I was from first-person... this can be confusing and frustrating at times. Be aware of such issues if you have more people helping you write better.
Use version control and suggestion mode
This one is an obvious one, one thing very often not utilized in Google Docs is naming a particular version - which allows for creating a clear saving spot to refer back to.
Also if you edit someone else document use comments and suggestions unless the author was perfectly clear that you can directly edit the document.
Know who you are writing for
It is best if the person peer-reviewing your document is a person from the group that will read and utilize your document. If you are writing a meeting note for your team vs. a quarter plan for board members, you will need to explain different terms and use different language. It is great if the person helping you check your writing has the same level of knowledge of the topic as your document audience.
If you only are helping others - trade places, and write yourself.
If you only write - trade places, and help someone write better.
You start to look at things differently when on the other end.
Text copywriting is not a code review, or is it?
I noticed that when I'm doing a code review I take much more time to discuss and understand other person's view. If in doubt I ask other people for input. In the case of documents I often feel rushed and sometimes even accept suggestions that I don't agree with. Maybe I trust that others write better text than I do, and in the case of code, I feel the opposite 🤷♂️. It might be due to me having less experience in text writing than coding (isn't it also text writing just more precise? 🤔).
It should be more popular for documents (also business ones) to use code review and merge-request approach by having a clear process for this and not relying on a chaotic approach of commenting Google docs in a random manner, with comments that will disappear forever once applied or denied. Also we should put in the document itself who helped us and recognize their work.