You know the 3 top issues that couples tend to fight the most about (not in any particular order): children, sex, and money. These 3 topics tend to trigger the most tension because people have such deep connections & beliefs about them; however, they are still an important part of a relationship and it's important such topics aren't avoided.
So how can you minimize such conflicts? Begin talking about them BEFORE it becomes an issue. Talk about the value of money (how you like to save/spend/etc.), how you want to raise the children, likes & dislikes in the bedroom as soon as possible! Don't wait until you find yourselves confronted with the issue. If you're dating and see your relationship going towards a serious path, discuss these issues NOW. If you're already married, continue such discussions as they come up for either one of you.
Having ongoing discussions about your expectations will help you understand your partner and yourself better in relating to one another & enhance your relationship.