The best place to start is at the top. The divinely inspired, inerrant, and revealed Word of God has helped millions of people to pray through the ages. Just reading the Bible is itself a prayer when done meditatively; each word, sentence, paragraph, and chapter are studied and given proper reflection.
Since antiquity, Jews and Christians have prayed the Psalms from the Bible. Whether it is from the Breviary (Divine Office or Liturgy of the Hours) or straight from the Bible, reading the Psalms is very good prayer. The Gospels contain the words and deeds of Christ, so reading any of them (Matthew, Mark, Luke, or John) meditatively is also excellent prayer and will enhance your prayer life. The more Sacred Scripture we read and use in prayer, the better we know the Lord since we are reading His words to us.
Many non-Catholics have problems with praying the rosary, since initially they only see it as repetitive prayer. Jesus rebuked the rattling on of prayers just for the sake of quantity. Likewise, Catholics are encouraged to pray the rosary often, but quality is what counts, not quantity. The rosary begins with the Apostles’ Creed and uses the Hail Mary (which comes from the mouths of the Archangel Gabriel and Saint Elizabeth as recounted in Luke 1:28, 42) and the Lord’s Prayer or Our Father (taught by Christ Himself). It meditates on the mysteries of Christ, from His annunciation and birth to his death, resurrection, and ascension. Praying fifty Hail Marys in one rosary can be very relaxing. The repetition does not give you more grace than if you prayed ten rosaries, but the more the rosary is prayed, the better the mind can transcend the clutter and noise of this world and connect with heaven.
Joining a prayer group which meets daily, weekly, or monthly is another help, as well as reading Bible commentaries, the Catechism of the Catholic Church, the writings of the Church Fathers, and tried and true spiritual classics. Here is a list we suggest:
1. John A. Hardon, SJ, Catholic Lifetime Reading Plan (An Anthology)
2. Saint Francis De Sales, Introduction to a Devout Life
3. Saint Therese Of Lisieux, Story of a Soul
4. C. S. Lewis, Screwtape Letters
5. G. K. Chesterton, Orthodoxy
6. Saint Louis De Montfort, True Devotion to Mary
7. Saint Augustine, The Confessions
8. Archbishop Fulton Sheen, Life is Worth Living
9. Francis Fernandez, In Conversation With God
10. Saint Josemaria Escriva, The Way
11. Fr Benedict Groeschel, CFR, Arise From Darkness