Lent begins on Ash Wednesday. It is a time of penance to expiate our sins, to develop virtue and to configure ourselves to Christ. Before Lent begins, however, is Shrovetide.
The English term "shrovetide" (from "to shrive", or hear confessions) is sufficiently explained by a sentence in the Anglo-Saxon "Ecclesiastical Institutes" translated from Theodulphus by Abbot Aelfric about A.D. 1000: "In the week immediately before Lent, everyone shall go to his confessor and confess his deeds and the confessor shall so shrive him as he then may hear by his deeds what he is to do [in the way of penance]". (Catholic Encyclopedia)
To make a good confession, you must
Take your time – the longer it has been since your last confession, the more time you will need to rightly remember your sins (e.g. someone who goes to confession every month will be able to examine his conscience properly within ten minutes’ time; someone who hasn’t been to confession for six month or more, may need to take half an hour or more to cover the whole time).
Make two separate lists: one for mortal sins and the other for venial sins! It is your responsibility to make it clear to the priest which of your sins are mortal sins (i.e. grave sins committed, both knowingly and willingly).
Remember that mortal sins need to be confessed with their exact (as exact as possible) number, and also various circumstances that might change the importance of that sin (e.g.: someone who confesses “I have injured someone” – if he has injured a player in the course of a game of rugby, the matter may be rather unimportant, but if he has injured his mother in anger, this increases the malice of his sin!). Do not hesitate to use a checklist, at least from time to time, otherwise you might end up forgetting certain categories of sins through routine.
Contrition is the most important part of your confession since only sins regretted can be forgiven. A true contrition includes the firm resolution not to commit any grave sin again and to avoid the proximate occasion of those sins. Perfect contrition is better (i.e. to regret your sins for the love of God...), because it takes away the sins even before the confession (but necessarily includes a desire to confess one's sins at the earliest opportunity; but imperfect contrition (i.e. to regret your sins for fear of being punished with Hell) is sufficient for confession, since the sacramental absolution replaces what is lacking in your contrition.
To confess your sins means accusing youself. The sacrament of penance (confession) is a process, a tribunal; and you are the accuser, and the one to be judged. So, don’t confess saying “Lying, stealing, cheating...” but: “I have lied; I have stolen...” This means confessing your sins humbly and sincerely.
If you are uncertain if a sin is mortal or venial, mention this to your confessor! This will put your conscience at peace, instead of leaving you with a doubt.
Listen to the priest’s counsels and admonitions, answer his questions simply and truthfully. The priest does not ask unnecessary questions out of curiosity, but because he needs to judge ‘your case’, and to do so, he needs a clear picture of the state of your soul and conscience.
If you do not hear or understand what the priest is saying, in particular with regards to the penance imposed, tell him immediately. You will be at fault if you cannot do your penance because you did not hear or understand!
Remember that, whatever you say in confession, is sealed under the seal of confession. The priest, or any other person, who might have heard what was being said in confession, may never reveal anything that concerns your sins, or any other circumstance that could bother or annoy you. Priests have died for the sake of not violating the confessional seal. Be careful not to confront a priest with things said by him or by another priest in confession. It is impossible for him to give you an answer. If you want counselling on matters concerned with your confession, you will first have to give permission to the priest to talk about this confession; or he may ask you to briefly tell him again what the particular problem was, since normally by then he has forgotten what you had said in confession. The penitent may talk about his own confession, and about the priest’s words; but remember carefully, that quoting a priest’s counsels etc. out of context, can easily mislead people to whom you pass them on, since they don’t know which sins you have committed, and hence, why you have been given such and such counsel!
The penance must be done in the exact way indicated by the priest. You cannot alter the penance (e.g. if you cannot find the prayer you are demanded to say...), but you need to go back to the priest, and ask him, reminding that your question is concerning confession, and you allow him to talk about things related to this confession (see above).
It should be fulfilled as soon as possible. If you did not fulfil a penance, you are bound to do so in discovering the fact. Penances do not ‘expire’. You owe them to Divine Justice, which has pardoned you in the tribunal of confession.