If you follow these, you'll be fine:
Don't hate on minorities
Don't post AI content outside of communities made for it
Don't insert yourself into communities where you don't belong, eg:
- Don't comment "As a man, ..." in WomensStuff
- Don't debate the validity of trans folks on Blahaj
- Don't criticize China in any way on lemmy.ml
DO NOT post anything negative about Linux (unless you're comparing it to BSD, of course)
Sometimes it's a bit harder not to offend than on reddit, because posts may hit your front page from an instance that was created as a safe space for a group you're not part of, and they may react harshly to you budding in.