For the dead, "Eternal rest give to them, O Lord; and let perpetual light shine upon them."
My Jesus, mercy!
My God and my All!
Jesus, be not my Judge, but my Savior!
May the most just, most high, and most amiable will of God be done in all things; may it be praised and magnified forever.
Jesus, my God, I love Thee above all things.
Jesus, grant me an increase of faith, hope, and charity, a contrite and humble heart.
May the Sacred Heart of Jesus be loved everywhere.
O Heart of Jesus, I implore, that I may ever love Thee more and more.
Heart of Jesus, be my love.
Heart of Jesus, burning with love for us, inflame our hearts with love of Thee.
Mary. ( This icon and others can be found at the Icon Archive.)
Jesus, Mary and Joseph, I give you my heart and my soul.
Jesus, Mary and Joseph, assist me in my last agony.
Jesus May and Joseph, may I breath out my soul in peace with you!
Mary, conceived without sin, pray for us who have recourse to thee.
Our Lady of Lourdes, pray for us!
Jesus, Mary, Joseph!
Mary, Mother of all Christians, pray for us.
Sacred Heart of Jesus, Thy kingdom come!
Heart of Jesus, I confide in Thee.
Lasance, My Prayer Book, Benziger Brothers, 1908, pp.260-63.
"Virgin Mother of God, Mary, pray to Jesus for me." St. Philip Neri, ibid. p. 279.
"Jesus, meek and humble of heart, make my heart like unto Thine! Ibid. p.280.
At the elevation of the host during mass or exposition of the Blessed Sacrament: "My Lord and my God!" Ibid. p. 292.
"We adore Thee O Jesus Christ, we bless Thee; because by Thy holy cross Thou hast redeemed the world." Ibid. p. 292.
My God, grant that I may love Thee, and grant that the only reward of my love will be to love Thee always more and more.
"O Sacrament most holy, O Sacrament divine, all praise and all thanksgiving be every moment thine." Ibid, p. 293.
May the most just, most high, most amiable will of God be done in all things, be praised and magnified forever. Ibid. p. 297.
Holy Virgin Mary, immaculate Mother of God and our Mother, speak thou for us to the Heart of Jesus, who is thy Son and our Brother. Ibid. p. 298.
Lamb of God, Who takest away the sins of the world, have mercy on us. Ibid. p. 299.
May the Heart of Jesus in the Most Blessed Sacrament be praised adored, and loved with grateful affection, at every moment, throughout the world, even to the end of time. Amen. Ibid. pp. 360-61.
O Mary, who didst come into this world free from stain obtain of God for me that I may leave it without sin. Ibid., p.415
Holy Archangel Michael, defend us in battle, that we may not perish in the tremendous judgment. Ibid., p. 433.
The above prayers were all "indulgenced", i.e. encouraged by the pre-Vatican II Church. They can be adjusted to more modern language, and to suit your temperament. You may find one or two to be really useful in times when you are "stuck", when you are not sure what you want to say.
Invocations that are encouraged in the post-Vatican II church can be found in the Enchiridion of Indulgences appendix.