To obtain a favor, St. Don Bosco generally advised a Novena to Our Lady Help of Christians. He had a singular devotion to the Hail Holy Queen and advised some work of charity as thanksgiving for graces obtained.
O Mary, powerful Virgin, thou art the mighty and glorious protector of holy Church; thou art the marvelous help of Christians; thou art terrible as an army in battle array; thou alone hast destroyed every heresy in the whole world. In the midst of our anguish, our struggles and our distress defend us from the power of the enemy and at the hour of our death receive our souls in paradise. Amen.
Here mention your Petitions
Say Our Father, Hail Mary, Glory be to the Father, three times
Hail, Holy Queen, Mother of Mercy, our Life, our Sweetness, and our Hope. To Thee do we cry, poor banished children of Eve. To Thee do we send up our sighs mourning and weeping in this valley of tears. Turn then, most gracious Advocate, Thine Eyes of Mercy toward us, and after this our exile show unto us the Blessed Fruit of thy Womb, Jesus. O clement, O loving, O sweet Virgin Mary. Pray for us O Holy Mother of God. That we may be made worthy of the promises of Christ.