What are the unwritten rules (or honourable play styles) you play by?

I saw someone mention the "unwritten rule" of no fighting at outposts which sparked a debate on:

1. The fact that it was more a playstyle than a rule
2. The fact that there are no unwritten rules at all and you can do whatever you want whenever you want

So I'm interested in hearing your thoughts and if there are any honourable "rules" or otherwise that you stick to