When seeking to understand Mormon doctrine, knowing the written Scriptures of the LDS church is not enough. Mormons have no concept of a closed canon (in fact, they tend to ridicule such an idea). There are other ways in which Latter-day Saint teachings are established.
The Second Level: Official Statements from Presidency
The ninth Article of Faith states, "We believe all that God has revealed, all that He does now reveal, and we believe that He will yet reveal many great and important things pertaining to the Kingdom of God." For Mormons, God continues to reveal himself and his ways to them. Fundamentally, this revelation comes through the living prophet and president of the church. Thus, official statements by LDS prophets as well as official statements by the First Presidency are authoritative for Mormons. They should also be consulted when examining Mormon beliefs.
The Third Level: Material from the Presidency and General Conference Statements
Materials that are produced by the First Presidency of the LDS church itself with the intent of teaching church members what they believe should also be considered as accurate and helpful sources of church doctrine. One very important book in this regard is Gospel Principles.
Additionally, statements by general authorities during the church's general conferences carry a lot of weight. Since all church members are supposed to watch these general conferences, and since these conferences provide a platform for LDS church leaders to address members, what these authorities say is often important in the beliefs of Latter-day Saints.
The Fourth Level: Other Statements from General Authorities
Once we get down to the fourth level, the authoritativeness can be relatively low. Nevertheless, the general authorities tend to be highly regarded by church members. With this in mind, what they say and write outside of general conferences can also be influential.
The Fifth Level: Other Writings
Some models do not include a fifth level. Nevertheless, I believe that such a level exists in the lives of many Mormons. While these writings may have no "official" authority within the church, some Mormons may see them as authoritative in some sense. As an example, we have already seen that many Latter-day Saints have looked to McConkie's Mormon Doctrine for a summary of their beliefs. Others draw heavily from contemporary Mormon scholars and apologists. We cannot assume that all Mormons believe what is written at this level, but we can recognize that Mormons often will turn to others in having their beliefs explained and defended.
The Solution
This "hierarchy of authority" provides a strategy for understanding, examining, and critiquing Mormon doctrine. It also allows us to keep various LDS material in perspective. With these levels in mind, I hope that we can accurately discuss, debate, and refute the claims of the LDS church while pointing Mormons to the true Jesus Christ.
(I have based my hierarchy on James R. White, Is the Mormon My Brother? Discerning the Differences Between Mormonism and Christianity, 23-42. To see this kind of model implemented, see Cky Carrigan's PhD dissertation, "An Assessment and Critique of the Distinctive Christology of the Church of Jesus Christ of Latter-day Saints (Mormons).")


