How to make a good examination of conscience:
One who goes to Confession frequently need not spend too much time in examining his conscience, wearying his mind to no purpose and giving scrupulosity a chance to gain a foothold. The examination should be calm, but earnest.
The first step is earnest prayer to the Holy Ghost to ask for light and grace to know and detest one's sins. The examination should bring to mind the time of the last good Confession and whether or not the penance was performed. It should cover one's sins of thought, word, deed, desire, and omission:
1) Against the Commandments of God,
2) Against the Precepts, or Laws, of the Church,
3) With regard to the Seven Capital Sins,
4) Regarding neglect of the duties of one's state of life, and
5) Concerning the Spiritual and Corporal Works of Mercy omitted.
Those who examine their conscience every night and go to Confession will readily remember any mortal sins that have been committed. But for such that go to Confession rarely and are addicted to sinful habits, or have made a number of unworthy Confessions, more than a passing glance at their conscience is needed. Such persons ought to begin their self-examination a few days before going to Confession, remembering that this Confession may perhaps decide the fate of their soul for eternity.
~Confession It's Fruitful Practice