- Listen more than you talk.
- When in doubt, repeat what they just said back to them, to confirm that you understand correctly.
- Try to never speak negatively.
Qualify your negativity. Don't say "I hate <person>", say "I hate <person> when they do <action>". This gives <person> less reason to stop caring about what you think: if you hate them no matter what, why bother trying to improve? It also gives them a obvious path for what they can do to make you happy: work on <action>. (Note that you shouldn't say you hate something, that is highly negative).
- Disagree by asking questions, not stating their incorrectness.
- Always thank people. If you can't think of something to thank someone for, just thank them for their time.
- Giving personal advice is hard. My usual strategy is to ask them questions until they figure out for themselves what they want.
- Work with people on what you agree with, don't argue about what you don't agree with. Eventually your perspectives may come closer, based on your shared experience.
- Privacy is important, but act like someday, everyone will know your actions. In a year, could you justify what you have said? (This comes from something I read long ago, which said "When considering whether something is ethical, ask yourself 'would I feel comfortable having this reported on TV?'")
