The Catechism says that we must confess all mortal sins of which we are aware, following a diligent examination of conscience. It also advises that, while it is not necessary, it is good to confess our everyday faults (venial sins).
With that said, note that the ritual for the sacrament of reconciliation gives us a five-page examination of conscience in Appendix III. The examination follows the Ten Commandments under three general headings which look at our relations with God and each other and our efforts to grow in the likeness to God.
Any spiritual director would suggest that penitents using an examination of conscience look for what we call the predominant fault. Try to determine what drives you in your daily life. What motivates your actions? What determines the decisions you make in family life, in social life, in your business dealings? And look not just at the wrong you may have done but also at the good you left undone.