1) Be understanding. Instead of talking immediately, try your best to lend a listening ear first. Everybody wants to share something and to be heard. Let the other person to talk first and under where he's coming from. Use polite words when you're talking. Make it your goal to always come to agreement with the person you're speaking with.
2) Be honest. Don't say one thing when you mean the other. Express your thoughts and wants with all honesty. This will keep you from having unmet expectations or unwanted disappointments. By being honest, you're protecting yourself from getting hurt. This prevents you from hurting others as well.
3) Be a giver. Giving is better than receiving. Giving is not all about material things or money. You can be generous with your affection, compassion, praise, time, trust or what have you. Most of us, engage with others with the intentions of acquiring something that will be beneficial to them. Such attitude will keep you from having good and lasting relationship with others. Try your best initiate generosity and you will be surprised with the good thins that will follow.