The Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204), in the second chapter of his Hilchot Teshuba (listen to audio recording for precise citation), describes the way a sinner should conduct himself as part of the process of repentance. He writes that a penitent sinner should regularly cry and pray to God for forgiveness, and give as much charity as he can afford. The sinner should also distance himself as much as possible from the matter in which he had sinned. In some instances, it would be appropriate for a penitent sinner to change his name, in order to proclaim that he is now a different person, and not the same individual who committed the wrongdoing. A person should fundamentally change his entire lifestyle, following the path of piety and Torah observance. Moreover, the Rambam writes, it is laudable for a sinner to accept a self-imposed exile, and relocate in a place where he does not know anybody, as this engenders a sense of humility and submission.
The Rambam writes that if a person repents after committing a sin "Ben Adam La’habero" – against another person – it is laudable for him to publicize the fact that he committed the offense and sincerely regrets what he did. If a person refuses to disclose the sin, he is considered arrogant and his repentance is incomplete. However, when it comes to sins "Ben Adam La’makom" – that one committed against God, and not against one’s fellowman – to the contrary, he should not publicize the act. It is considered brazen to openly tell people about a sin one committed against God. One should rather confess his sins privately, only to God, and mention in public only the fact that he sinned in general, without specifying the act he committed.
The Rambam then proceeds to discuss the unique status of the Aseret Yemeh Teshuba (Ten Days of Repentance) with regard to repentance. Even though repentance and prayer are certainly always beneficial, he writes, Teshuba is especially beneficial during the ten days from Rosh Hashanah through Yom Kippur, when God makes Himself closer and more accessible, so-to-speak. The Rabam adds that this distinction applies only with regard to individual prayer and Teshuba. When a congregation repents, their repentance is accepted at any time. With regard to congregational prayer, any day of the year is as conducive to having prayers and repentance accepted as the Ten Days of Repentance.
Yom Kippur, the final of the Aseret Yemeh Teshuba, is designated as a day of repentance and forgiveness, and therefore every Jew bears an obligation to confess his sins and repent on Yom Kippur. The Rambam writes that one should actually confess the day before Yom Kippur, before he partakes of the final meal prior to the fast. One must be concerned that he may choke on his food and die during this final meal, and therefore one should recite Vidui (confession) during Minha on Ereb Yom Kippur, before eating the meal. The Rambam notes that Vidui must be repeated during every prayer on Yom Kippur – Arbit, Shaharit, Minha and Ne’ila. The Vidui service is recited in the individual prayers immediately after the Amida service. During the Hazzan’s repetition of the Amida, he recites the Vidui as part of the fourth Beracha of the Amida prayer.
Summary: It is proper for a penitent sinner to frequently pray for forgiveness, give charity, conduct himself with humility and submission, and resolve in his mind that he is a completely different person. Prayers and repentance are especially beneficial and effective during the ten days from Rosh Hashanah through Yom Kippur. There is an obligation for every person to confess and repent on Yom Kippur. One confesses in Minha on Ereb Yom Kippur, and then at every prayer service on Yom Kippur.
