I think it's good to use a mixture of psalms, outloud prayers, and also silent prayers. I read from a prayer book, and also psalms, and this helps focus and soften the heart in order to pray with my own words with sincerity.
"When you are saying your prayers---and especially if you have a rule of prayer according to a book, do not hurry from one word to another without feeling its truth, without laying it to your heart; always strive to feel with you heart the truth of that which you say. Your heart will oppose this---sometimes by slothfulness and stony insensibility, sometimes by doubt and unbelief, sometimes by distraction and deviation of the mind to earthly objects and cares, sometimes by the remembrance of the offences of your neighbour, and by a feeling of revenge and hatred towards him, sometimes by the representation of worldly pleasures, or by the representation of pleasure derived from reading novels and worldkly books in general. Do not spare yourself; conquer your heart, and offer it to God as an acceptable sacrifice: 'My son, give me thine heart.' Your prayer will unite you to God and all heaven, and you will be filled with the Spirit and the fruits of the Spirit---righteousness, peace, joy, love, meekness, long-suffering, and wholehearted repentance."---St John of Kronstadt