Here's a starting point for documenting a specific issue with a co-worker. Adapt this to your circumstance.
Issue: Suppose your co-worker makes comments about your culture that you feel are disparaging. You want him to stop. You don't want to make a big deal.
Your questions are:
- What should be written down? What should not?
- Should witnesses be informed that an event was recorded? Should they sign it, or give their agreement in some way? Which way?
- Where should the document be stored? At work? At home?
- Who, in the company, should know about the existence of that document?
- What's the value of that document?
Let's tackle these in a different order, starting with the purpose.
What's the value of that document?
The value or purpose is to try to create an objective record (or as objective as possible) about what is going on, so that others who are not present during the events, can get some sense of what happened.
A good record will elevate "your side of the story" into a trustworthy narrative.
Imagine YOU are the boss. Two people come to you to resolve a fight. One just has some mumbling dissatisfaction. The other has a log of dates, times, and places where they disagreed, a summary of the disagreement, and sometimes specific quotes. You see from looking at the summary that (a) it's been going on for 3 months, (b) it follows a pattern, and (c) the person keeping the log has written a pretty dispassionate account.
Who do you tend to believe? Who is helping you see the fuller picture? Whose account will hold up in court if this doesn't get resolved?
What should be written down? What should not?
You are a Sikh and wear a turban. Your co-worker refers to you as a "rag-head" to your face.
Within a few minutes of the event, write down the date, time, and location of the comment, and the exact words as best you recall them.
If you feel like gently confronting the comment (and thus confronting the speaker) I urge you to try "Non-Violent Communication."
A quick summary of NVC: Observe, Feel, Need, Request.
Observe: "Joe, I hear you calling me a rag-head."
Feel: "You may not be aware that when you use that term, I feel disrespected by you."
Need: "I need both you and me to feel respected at work."
Request: "I request you not use that term."
If you do say this (or say anything) then write that down also. Keep a log of these incidents. Describe things as they would appear on a video camera.
Don't say "he got in my face" which is subjective. It's more objective to say "he stood less than a foot away from me."
Don't say "he was angry" which is an interpretation. It's more objective to say "he raised his voice, interrupted me, slammed his fist on the table, and slammed the door when he left."
What should not be written down:
- Subjective opinions without observable facts (i.e. don't just write "Joe was a jerk again today")
- Complaints without requests. Every complaint contains a hidden request. Make the request. Then log it.
- Self pity. Save that for your personal journal or your therapist.
Should witnesses be informed that an event was recorded? Should they sign it, or give their agreement in some way? Which way?
Not needed in this case. I wouldn't. There may be scenarios where you should.
Where should the document be stored? At work? At home?
I'd keep it in a personal Google Drive document or even better in a spiral notebook that I scan, and keep the scan online in a personal account. Paper notes with dates/times are hard to fake and look good in court. You may not want to go to court, but good habits should be built from the very beginning.
Who, in the company, should know about the existence of that document?
Nobody at first. Maybe Joe will respond to your requests. If you have to ask a third party for help (HR, your boss, a union rep, etc.) then you can share a summary of what you wrote, or a COPY (never the original). Only share things relevant to the current issue.
I teach managers to keep written notes on the good and bad performance of every one of their direct reports. It makes performance appraisals easy and accurate.