I struggled with church doctrine and history for years before I could bring myself to admit the possibility that the church might not be true. Once I allowed for that possibility, my testimony crumbled like the proverbial house of cards. In hindsight, I see that the church had a strong hold on my belief system. This realization has caused me to reflect on my "testimony" and how it was constructed. For this reflective exercise, I used two Ensign articles to articulate the church's teachings on testimony: "The Soil and Roots of Testimony" by Elder John K. Carmack of the First Quorum of the Seventy (Ensign, Nov. 1988), and "The Importance of Receiving a Personal Testimony" by Elder Robert D. Hales of the Quorum of the Twelve Apostles (Ensign, Nov. 1994). Although I am only referencing two talks, the teachings contained therein are commonly preached and can be found in many more sources.
The first step in gaining a testimony is having a desire to believe. This principle is taught in two formats: "You must want to know the truth" and "You must want to believe." I have no problem with the former. However, my experience has been that this brand of desire is quickly abandoned when someone complains that their reading and praying aren't bringing the promised spiritual confirmations. When this happens, people are pointed to the latter principle, that one must want to believe. Alma chapter 32:27 is often quoted: "If ye can no more than desire to believe, let this desire work in you." One cannot be an impartial judge between truth and falsehood while desiring one outcome over another. If I want to believe the church is true, then I will accept supporting evidence and discount damning evidence. Likewise, if I want to believe that Joseph Smith was a fraud, then I will accept supporting evidence and discount anything to the contrary. Obviously, any serious attempt to discover truth should at least try to be unbiased (if that is possible). Nevertheless, in the church people seeking to find truth are taught that they first need to desire to believe in the restored Gospel, and then they will be on the road to obtaining that belief. While this is a true statement, it illustrates the distinction between constructing a belief and finding truth.
Another step in gaining a testimony is looking for a specific answer to prayer. People will usually experience many "non-answers" for every one good emotional answer to their prayers. When people confess that they haven't yet received an answer to their prayers, they are given assurances not to worry, that they will receive their answer in time if they are faithful. The problem with this approach is that by predefining what the "correct" answer is, a person is conditioned to ignore any other type of answer. These "non-answers" are only considered as such because they were predefined that way. In fact, they could be interpreted as confirmations that the church isn't true or that prayer doesn't work or any number of different answers. Coaching people to ignore these experiences is making their quest for a testimony a self-fulfilling process rather than a spiritual quest for truth.
Here is an example from the experience of President David O. McKay (Francis M. Gibbons, David O. McKay):
One day while herding cattle in the foothills near his home, he sought a testimony through prayer. He said: "I dismounted, threw my reins over my horse's head, and there under a serviceberry bush I prayed that God would declare to me the truth of his revelation to Joseph Smith." He prayed fervently and sincerely with as much faith as he could find within him. When he finished his prayer, he waited for an answer. Nothing seemed to happen. Disappointed, he rode slowly on, saying to himself at the time, "No spiritual manifestation has come to me. If I am true to myself, I must say I am just the same 'old boy' that I was before I prayed" (ibid.). A direct answer to this prayer was many years in coming. While serving a mission in Scotland, Elder McKay received a powerful spiritual manifestation. He later commented, "Never before had I experienced such an emotion...It was a manifestation for which as a doubting youth I had secretly prayed most earnestly on hillside and in meadow. It was an assurance to me that sincere prayer is answered 'sometime, somewhere.'"
So, the lesson from President McKay is to ignore every prayer which didn't result in an emotional experience, and cling to the one or few times when prayer and emotion coincide. Sarcasm aside, I can't help but think that people often—or at least occasionally—have emotional experiences when contemplating and praying to their God. I'm amazed that John Taylor went years before his prayers about the church yielded an emotional experience.
By the way, you also need to ignore the fact that people in all religions have emotional experiences that they attribute to a confirmation of their beliefs.
Another important aspect of gaining a testimony is not to rely on reasoning and logic. With this caveat in the search for truth, one's testimony becomes a "shield of faith" (Hales). One cannot be convinced that the church isn't true because no evidence supporting that conclusion is considered. If it doesn't support the church, then you should chalk it up to an attempt by Satan to pull you away from the truth. If something seems absolutely ludicrous, contradictory, or impossible, then we should just remember that we once had a good emotional experience and chalk up troublesome issues to man's inability to comprehend the things of God. Common boasts among members include: "Our testimony is a measurement of our faith" (Hales) and "I have a whole box of unanswered questions, none of them threatening to my testimony" (Carmack).
Also, you should immerse yourself in the church through frequent scripture study, attendance, service in callings, etc. In this way, you will start seeing the world through the appropriate lens. You will interpret your experiences in ways that confirm your worldview. This also allows social pressure to increase.
And most abhorrently, you should profess belief in order to actually gain that belief. Elder Boyd K. Packer has said repeatedly, "A testimony is born in the bearing of it." Elder Hales says, "Share (your) testimony...You will find when you share your testimony it becomes stronger." If you tell other people that you believe something even when you don't, then cognitive dissonance will begin to work on you, i.e. you will begin to believe in order to decrease the internal conflict caused by the discrepancies between what you say and what you believe. My mission president captured the essence of this approach in his advice to all his missionaries, "fake it 'til you make it." Yes, he was referring to our testimonies.
Lastly, one must be humble and willing to acquiesce to authority figures. Of course, all the authority figures in the church are telling you that the church is true. They also teach that a lack of belief is the fault of the individual, not a fault of the church. "The gospel seed must be sown in good ground" (Carmack). If someone studies, ponders, prays and nevertheless finds the church lacking, then one of the following causes can be attributed to this failure (Carmack):
If I reverse the above sins, then I can see what is requisite to maintain a testimony.
When I consider these steps now, I conclude that they are designed to get people to believe in the church, but have no bearing on helping them search for truth.