Euan Cameron says, in Interpreting Christian History, page 126-7, the early Church had no cult of saints, but around the time of the persecutions, Christians began to commemorate their martyrs, to inspire their successors and protect their memory. A little later, some Church Fathers decided that the saints must still feel the same concern for the faithful as when they lived, so the saints must be praying for us. Later still, people supposed it was appropriate to pray to the saints in heaven, to call on them as patrons, and ask for favours and protection. Thus it became established practice to pray to saints for intercession. Vivian Green says in A New History of Christianity, p118, there were instances of men beating the saint's image because the saint had not responded to their prayers.
Green also talks about the special reasons for praying to Mary. He says (p117) that St. Bernard declared, “If you fear the Father there is Christ the Mediator. If you fear him, there is the Mother, pure humanity. She will listen to you. The son will listen to her, the Father to him.”
The Protestant position is strongly against praying to saints. Martin Luther believed that the veneration of saints had turned into the worship of semi-divinities who were addressed exclusively for some need, with no reference to Christ. He also objected to the cult of relics to raise money. In Smalcald Articles, he called the invoking of angels and saints, praying to them, keeping fasts and festivals for them, saying masses and offering sacrifices to them, and assigning to them special functions, “idolatory”.
It seems that there is a divide between the position of the Catholic Church (and Orthodox Church) and other Christian denominations. You will be guided by which denomination you belong to.