The saints recommend a spiritual director, one with learning and experience. Some experiences similar to those of Contemplative Prayer can be brought on by the evil one. By their fruit one shall know them. Saint Teresa of Avila says that instead of peace, one is greatly distrubed afterwards, and the experience does not cause change within a person.
The good fruit is that a person changes his life for the better. He is able to forgive those who hurt him. He is able to love strangers and is willing to care for them. He cares about the salvation of the world. Prejudice leaves his heart and he strives to mature in virtue and his faith. He tries to trust God and to do something for Him, realizing His providence and graces given to him, for which he is exceedingly thankful and full of praise. He asks forgiveness from others. He is not distrubed over people slandering or mocking him nor over lack of consolations in prayer. There is a willingness to suffer. Things of the world no longer interest him.
St. Teresa of Avila, Interior Castle, trans. E. Allison Peers (New York: Image Books, 1961) Fourth Mansion, ch. 3, p. 91.