There are two extremes with prayer, both of which can cause problems. The first is when our prayer life is based solely on routine. In this sense, everything becomes a ritual in which more spontaneous elements are seen as foreign to true devotion. The other extreme is when we think that prayer is only about spontaneity and creativity, and instead of prayer being transformative, it becomes about fulfilling our personal whims.
The proper balance is a prayer life that incorporates both formal and informal prayer. In this sense, we should have aspects of our prayer life which are vocal prayers and liturgical. Examples of this would be the rosary, the liturgy of the hours, litanies, etc. There are really way more formal prayers than one person would ever be expected to do. In addition to such examples of vocal prayer, there are also formats of formal meditation. These can be incredibly helpful in the beginning, but they are a means to an end and not an end in themselves.
In addition to the formal practices, we must set time aside for more spontaneous discursive meditation. This can be as simple as 10-20 minutes a day. In the beginning, it can be helpful to have specific topics and particular passages on which we meditate. Although this is advised by many writers and directors, we should not be afraid of being less structured. Similar to the formal meditations, these are meant to lead us to the more spontaneous sharing of the heart. They help train us on how to use our imagination in order to approach God.
In discerning your way through the different approaches to prayer, it is important to keep in mind the fruits of the Holy Spirit. These can help you discern that which is leading you closer to God, and that which is reinforcing your pride and self-centeredness. Spiritual friendships are also important in such discernment.