I think I would start with
1) identify the speaker's
goal, not their literal meaning. ("Those cookies sure look good.")
2) watch out for
pecking order
3) if you're going to say something negative about someone or feel forced to react to someone saying something negative, say it in a way that you are
willing to say it to their face.
4)start with
why (when giving instructions to an equal)
5) if it leads to better results, assume everyone is a little
more incompetant than they are malicious (unless shown otherwise) aka treat others more like pupils.
6) if you want them to change, admitting guilt shouldn't be required:
leave an exit (other than defeat) for them to where you want them to go.
Ex
Bad: "WHY DID YOU DO THAT!!!"
Better: "Oh, actually we have to keep this far away from the stove or it will burst and burn us."
7) if you care about them, ask them about their day
8) if you're grateful to them, tell them that.