Behold, I would exhort you that when ye shall read these things, if it be wisdom in God that ye should read them, that ye would remember how merciful the Lord hath been unto the children of men, from the creation of Adam even down until the time that ye shall receive these things, and ponder it in your hearts. And when ye shall receive these things, I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy Ghost ye may know the truth of all things (Moroni 10:3-5).
So first, of course, we must read.
And we must remember God's mercy through the ages, from the creation to now. That presupposes that we have some knowledge of God's mercy during that time. We must become acquainted with that mercy (some of which we get from reading the Book of Mormon, of course).
We need to ponder that mercy in connection with our reading of the Book of Mormon. To me this means that I must ask myself how the Book of Mormon is a continuing sign of God's mercy. How does it demonstrate His mercy to me?
Then when we receive these things (the book, an understanding of the mercy?), THEN we ask God in the name of Christ if these things are not true. I was always bugged by that wording as a missionary. Why should I have people ask if it's NOT true? I wonder sometimes if this makes that particular question more of an offhanded one: go ahead and ask if it isn't true, as if that isn't even a possibility.
Ask with a sincere heart. I can only judge that in myself, but a clue of my sincerity comes in the next phrase: with real intent. What do I intend to do with the knowledge I'm about to receive? If I intend to change my life because of it, then it seems I'm sincere. If I have no intention to change, then how real is my intent?
I must have faith in Christ. Faith is, of course, a motivating force in our lives, encouraging us to act according to the object of our faith. In this case, that faith is to be in Jesus Christ – as testified by the Book of Mormon, I assume. With that faith I would look forward to, among other things, the answer that the Book of Mormon IS true.
If I meet all those conditions, then the Holy Ghost will bear witness to me.
In subsequent verses we're taught to deny not the power of God, the revelatory power of the Holy Ghost and the gifts of the spirit which manifest themselves differently to different people. To me, Moroni says: Do not deny that an answer is possible. Have faith that one is possible. It will come.
It has for me.