In order to fight fair you must handle your anger righteously. Reacting with only your emotions will escalate your fight. Instead, be slow to anger as the Bible says in James 1:19 because it will lead to resolution and healing.
Talk: Discuss with your spouse the best way and time to approach each other when addressing an issue in your marriage.
Pray: Ask God to reveal to each of you times where you haven't fought fair and to help you restore any damage to your marriage caused by these fights.
Do: Create a simple list of ground rules based upon what you've learned from God's Word to use when you fight. Keep this list in a place where both of you can see it to remind you how to fight fair.