The three eminent good works are: prayer, fasting and almsgiving.
Raphael called the two of them aside privately and said to them: “Bless God and give him thanks before all the living for the good things he has done for you, by blessing and extolling his name in song. Proclaim before all with due honor the deeds of God, and do not be slack in thanking him. A king’s secret should be kept secret, but one must declare the works of God and give thanks with due honor. Do good, and evil will not overtake you. Prayer with fasting is good. Almsgiving with righteousness is better than wealth with wickedness. It is better to give alms than to store up gold, for almsgiving saves from death, and purges all sin. Those who give alms will enjoy a full life, but those who commit sin and do evil are their own worst enemies.
Catechism of the Catholic Church
1434 - The interior penance of the Christian can be expressed in many and various ways. Scripture and the Fathers insist above all on three forms, fasting, prayer, and almsgiving, which express conversion in relation to oneself, to God, and to others. Alongside the radical purification brought about by baptism or martyrdom they cite as means of obtaining forgiveness of sins: effort at reconciliation with one's neighbor, tears of repentance, concern for the salvation of one's neighbor, the intercession of the saints, and the practice of charity "which covers a multitude of sins."