In Orthodox Christianity, more than three hundred kinds of miraculous icons of the Blessed Virgin are known. Beginning with the first images of the Mother of God, written according to the tradition of the Apostle and the Evangelist Luke, the images of the Most-Pure Virgin gradually began to enter into the liturgical cult of the Church and into the private life of Christians. Great influence on the spread of the veneration of the Queen of Heaven was rendered by the dogmatic decision of the Third Ecumenical Council about the veneration of the Virgin Mary as the Virgin, made in 431 in Ephesus. From this moment the iconography of Our Lady receives a new development, which even the iconoclastic heresy could not stop. Over time, more and more icons of the Most Pure, began to appear, which were famous for their signs. Therefore, modern people often have a question, which image of the Virgin, what to pray about?
Immediately it is necessary to say that the very formulation of the question somehow reflects a certain pagan psychology in which a certain god or idol, for which it was necessary to make a sacrifice, was responsible for this or that sphere of human activity. Unfortunately, many people endure such an incorrect approach with regard to the icons of the Mother of God , forgetting that miracles and help are given to us by the Most Pure, and not by a concrete icon. Therefore, you can and need to pray for your needs before any manner of the Queen of Heaven available to you. After all, various miracles and help are done precisely by the faith of the worshipers. 
The Blessed Virgin gives his blessings and help through various icons. It so happened in history that through certain icons the Mother of God helped in specific needs or gave healing from specific diseases. Because those people who suffer from them, are more often treated with prayer to these specific images. For example, in the icon of the Mother of God Pantanasse (Alla), many people received healing from cancer. This encourages those who, for example, suffer from cancer, pray precisely for this image of the Virgin Mary. Although, again it is worth noting that it is also possible to pray in any other image of the Queen of Heaven, for prayer in the image of Panthana does not guarantee healing. Again, the main thing is personal faith in the help of the Mother of God and the purity of the soul. Thus, in church practice, cases are known where sick people traveled various holy places of the Orthodox world in search of healing, and they could receive healing after a hot prayer in the usual parish church.
The veneration of some icons of the Virgin depends also sometimes on the geographical place of the phenomenon of this or that image. For example, the Pochaev icon of the Mother of God is most revered in Western Ukraine, that is, where it was shown. Sometimes the wide distribution of the image is associated with the folk tradition of its use - for example, the Kazan Icon of the Pure One often bless the newlyweds for marriage. One way or another, it is worth noting that, because of our infirmities, we are more likely to handle prayers to miraculous images of our locality. The same thing can be said about the veneration of the saints, when, for example, in churches serve the saints of our land, and not Greek holy saints, although they are worshiped on the same day.
Therefore, answering the above question, we can summarize the following: to pray to the Blessed Virgin and ask her for help from ANY image of the Mother of God. The church does not have any exact prescriptions for praying for specific icons. Everyone has complete freedom in this matter. Most importantly, he remembers the words of the Savior, spoken by Christ to the blind man He healed: According to your faith be it unto you (Matthew 9:29).
