The basic requirement for a good confession is to have the intention of returning to God with your whole heart, like the prodigal son (in Luke 15), and to acknowledge your sins with true sorrow before the priest.
Modern society has lost a sense of sin. As Catholic followers of Christ, we must make an effort to recognize sin in our daily actions, words and omissions. An examination of conscience helps us do just that.
What is an examination of conscience?
An examination of conscience is a review of one’s past thoughts, words and actions for the purpose of ascertaining their conformity with or unconformity with the moral law (NewAdvent.org). In other words, an examination of conscience helps you identify the moments in your life when you’ve pleased God with your virtue or when, conversely, you have fallen into sin. If you examine your conscience in order to uncover and reflect on your sins, you can then bring those uncovered sins before God in the Sacrament of Confession and ask for His forgiveness.