Prayer

Martin Luther's advice to his barber about prayer, A Simple Way to Pray, emphasizes using things like the Lord's Prayer and the Psalms as ways to direct thought when praying.

ReformationSA summarizes some of Luther's advice:

Luther recommended that our prayers be numerous but short in duration. Luther taught that we should pray: “Brief prayers…pregnant with the Spirit, strongly fortified by faith…the fewer the words, the better the prayer. The more the words, the worse the prayer. Few words and much meaning is Christian. Many words and little meaning is pagan.”

The Lord’s Prayer and the Psalms were tools which Luther considered most important for any Christian’s prayer life. “A Christian has prayed abundantly who has rightly prayed the Lord’s Prayer.” The Lord’s Prayer is the model prayer of Christianity and it is not essentially a prayer of one individual, but a common prayer that binds all Christians together, uniting us with all believers, past, present and future, whether in Heaven, or on earth, in a Biblical Kingdom focused prayer.

Luther taught that praying the Psalms brings us: “into joyful harmony” with God’s Word and God’s Will. “Whoever begins to pray the Psalms earnestly and regularly will soon take leave of those other light and personal little devotional prayers and say, ‘Ah, there is not the juice, the strength, the passion, the fire which you find in the Psalms. Anything else tastes too cold and too hard.’” [more]

Thanks to Between Two Worlds and Stand to Reason for pointing the direction to this information.

Source: ReformationSA.com: Luther's Practical Program to Revive Your Prayer Life