To prepare for the Sacrament of Penance. Preparation for confession is called the retreat. In the days of the retreat you should go for service in the Church, was to be more serious about home prayers. Also during the retreat should observe the strict fast. This does not mean that you just should not eat meat and drink milk. These days you need to devote to deep thinking about their sins and transformation of life.
A day of confession a "beginners" face a psychological barrier: how can a stranger (priest) to reveal himself to, frankly, not the best. But we should not be afraid of this. In the confessional you say to the Lord, and the priest only assists you. Don't be afraid to talk about their sins.
A common "mistake" for the first time of confession is "whitewashing" in the eyes of the priest. We're talking about sin and immediately find a reason why it happened. If you've really repented of their sins, it means that you do acknowledge their guilt for their actions and not blaming others, and do not consider it an objective necessity.
If you came to Church for the forgiveness of our sins, be sincere with yourself. The sacrament of Penance requires effort on your part, not to do me a favor, come to confession. Don't be afraid to ask the priest a question, if you were not able to understand something. And most importantly, be honest with yourself and realize the importance of the sacrament of confession only for you, but not for others, friends and relatives. And the more it would be a mistake to believe confession is exclusively a cult event, deprived of a profound inner meaning.