Learn to compromise.
If you can learn to compromise, you'll find yourself in fewer disagreements. If you don't like something, then agree with your partner to find some middle ground. This also applies the other way. Be willing to come up with alternative solutions for things your partner doesn't like.

Don't say something you'll regret later.
Always consider your relationship like a glass. It is sturdy, tough, beautiful and clear when taken care of, but if it is mistreated or mishandled it can end up scratched, cracked or even broken. Take care in choosing the words you say when you are in the heat of the moment.

Give your partner enough space to express his concerns.
I'm sure you hate it when people interrupt you; give your partner the same respect -- even if you don't agree with what they are saying.

Make your relationship your first concern when you are in the middle of a disagreement.
This does not mean you need to bend over backwards for them or compromise your integrity. Just keep in mind that the person you are arguing with is your best friend, lover and soul mate. If you both keep that at the forefront of your mind in an argument, it will keep what matters most away from cruel words or intent -- your heart!