A prophet prepares for his calling as a prophet in the same manner that any other member of the church does. He attends church lessons, reads the scriptures alone and with his family, and ponders what he learns. He grows in his capacity to embody Jesus Christ's teachings, and he shares what he learns with others. In addition to these activities, a prophet often receives special guidance from God through dreams, visions, and prophecy. He may also receive certain anointingings that help him lead the church correctly. For example, Joseph Smith, the first prophet of the Church, said that he was commanded by God to rise up and pray about receiving this call. After praying about it, he received a revelation stating that he should go to Missouri and establish the Church there. Since then, every prophet has had similar experiences before they were called to lead the church. So, yes, prophets prepare for their call by seeking divine guidance through prayer and fasting. They also learn from those who are more experienced and take whatever steps they can to know how to lead the church correctly.