A major responsibility of those who are assigned the task of leading the prayers of the people is to actually make the prayers a common experience rather than another form of clerical control. The intercessions are in the hearts of the people (potentially, at least) and it is the job of the leader to get them out, to evoke them and help the worshippers to give them shape and feeling. Thomas Aquinas, the great medieval theologian, defined prayer as “the interpretation of desire.” What goodness should we desire and long for, in ourselves, our friends, our society, our broken world? When we pray for someone, we are giving voice to our desire for their ultimate good.
Two important aspects of the prayers of the people (or the intercessions, if you prefer) are covered by the words compassion and priesthood.   Compassion means “suffering with.” It is the Latin form of the Greek word sympathy, but it suggests a greater degree of involvement and a deeper level of feeling. Compassion involves standing with others in their suffering and not merely feeling sorry from a distance. As such, it is for Christians one of the attributes of God. The cross of Christ has been interpreted as an outward sign of God’s compassion. When we pray for others, we stand with them in their hopes and fears, and we also open ourselves to the possibility of them standing with us.
Coming before God with and on behalf of others is a priestly ministry.  Christian priesthood is not limited to those who have been ordained. The author of 1 Peter describes the Christian community as “a chosen race, a royal priesthood, a holy nation.”  (The ministers we call priests for complicated etymological reasons are, in fact, the elders or senators of the Christian community.) An English writer has said that intercession “is understood in the New Testament as a priestly ministry. It has a double movement. It is about entering the depths of the human predicament, and it is also about standing before God holding those predicaments in stillness.”
These two movements correspond to compassion and priesthood.
For more information go to page 30 of the Guidelines for preparing Prayers of the People   click here