Have the courage to face your weaknesses. Where are you lagging behind? What faults do you have? What mistakes do you repeatedly make? How can you improve in these areas?
Have the courage to admit you were wrong. It will be hard to look in the mirror instead of pointing out the faults of others. Or to admit your mistakes without caveats or giving excuses…just own them. Don’t say, “I only did this because…” or “I wouldn’t have done that if you didn’t do this.” That’s not admitting your mistake, not really.
Focus on your actions and how you can improve the situation, not on what you did right and what the other person did wrong. Don’t go in with the idea of having an “unwritten and unspoken agreement” (something in your head only) that when you apologize for X, the other will/should apologize for Y. That’s not how it works. Be sorry when you’re sorry. If you only use the words but don’t actually mean it, others will eventually see through it.