Most denominations require that you have a Master of Divinity degree from a seminary that is accredited by the Association of Theological Schools. In special cases, they may allow other degrees, but the Master of Divinity degree gives you the best preparation, so you should shoot for that if it is at all possible.
In most cases, it is not necessary to go to a seminary that is affiliated with your denomination. For example, I am ordained in the Disciples of Christ, but I obtained my degree from a United Methodist seminary, one of my courses was at an Episcopal seminary, and another was taught by a Catholic instructor at a Baptist seminary. I had classmates from a dozen different denominations, including Catholic, Episcopal, Presbyterian, and Seventh-Day Adventist. What is important is the accreditation, not the affiliation.
However, there are many who are self taught and have never attended a theology school and have growing and thriving churches and members who are prospering and gaining enlightenment about the Word of God.
What are the benefits of Theology school vs. self taught? Is one better then the other if done correctly with positive feedback from the public? Do you think theology is a bad idea for people who are divine? Is divine the same as being ordained? Is theology school an important part of ministerial development? Do you think the absence of school or training is one of the major problems with religion?