Fr. John Nicholas Grou, S.J. gives some excellent advice on how to make effective use of the Sacrament of Confession.Editing mine.
You are alarmed sometimes, because you feel no sorrow for sin, and your heart seems frozen; your act of contrition appears to be a mere formal set of words. You used to feel really grieved; love constrained your heart, and you were even moved to tears. Look well within yourself. See if you do truly detest the sins you are going to confess. If so, be at ease, and seek no further assurance. Your state of mind is probably better than when you were touched with sensible grief. Do not hesitate, therefore, to cast aside all fears and doubts and scruples on this subject: and, having taken the advice of your confessor, if necessary, then dismiss the matter entirely from your mind.
Besides, we do not excite contrition, as some suppose, by squeezing feelings out of our hearts, or moving ourselves to tears, but by humbly asking God to inspire our souls with true repentance, and then simply and quietly making our act of contrition. It is enough to do so once before confession, repeating it while the priest is giving the absolution.
Then as regards to the accusation; this is very often defective. We either say too much, or too little, by reason of self-love or shame. Any defects which result from ignorance or natural stupidity, will be remedied by the confessor asking such questions as he deems fit.
The accusation should be short and simple. No useless details, which often implicate other people; no circumlocution. If you have to say that you were impatient, or wanting in charity, do not make a long story of it. Some people think they would make a bad confession, if they did not repeat exactly all that was said to them, and all that they said in reply.
It must be clear and precise. No indistinctness, ambiguity, or disguise. Let the confessor understand the thing as you do yourself. None of those vague accusations, which merely take up time, and to which those are prone who like to make long confessions. You accuse yourself of self-love and pride. But these are vicious habits; they are not sins. Of slackness in God’s service: the exact way in which you are slack should be mentioned. You make lukewarm communions: what does that mean?
It must be thorough. No essential details should be suppressed. Together with the fault, mention the motive which induced it, and which is sometimes more sinful than the act itself.
Be absolutely sincere. If any fault is particularly humiliating, or if you fear reproof for it, do not leave it to the last: really humble souls begin with these. It is good also to mention one’s temptations, and explain in what they consist, even if you have reason to believe that you have not given way to them.
Shame sometimes leads us to conceal certain temptations. There is danger in this. It is a device of the devil to render a fall easier, and it generally succeeds.
Lastly, the accusation must be strictly true. Do not exaggerate, diminish or excuse your faults. Call that certain which you believe to be certain; doubtful what you consider doubtful. Scrupulous persons and those who suffer from temptations are apt to accuse themselves of having consented when they have not done so. When the confessor knows his penitents well, he should be on his guard and not take them always at their word; otherwise, he may well drive them to despair. Others think they should say more rather than less: they should, if possible, say neither more nor less. Those who are possessed of a strong and lively imagination should be on their guard against it in their confessions.
Early instruction on the subject of confession is exceedingly important because, at a certain age, it is almost impossible to correct the erroneous customs contracted by long habit.
This touching sermon on Confession explains it from the Priest’s perspective. It is well worth the eleven minutes.
Confession heals, confession justifies, confession grants pardon of sin. All hope consists in confession. In confession there is a chance for mercy. Believe it firmly. Do not doubt, do not hesitate, never despair of the mercy of God. Hope and have confidence in confession.
St. Isidore of Seville
Stabat Mater, Ora Pro Nobis!