Alma 17

As the sons of Mosiah prepared to serve their overwhelming mission to the Lamanites, Mormon teaches us how they prepared themselves for success in that -

"...they had waxed strong in the knowledge of the truth; for they were men of a sound understanding and they had searched the scriptures diligently, that they might know the word of God." (Book of Mormon | Alma 17:2)

By searching the scriptures they became priesthood men of knowledge and understanding, which really is receiving the mysteries of God -

"But this is not all; they had given themselves to much prayer, and fasting..." (Book of Mormon | Alma 17:3)

Combine prayer and fasting with knowledge and understanding -

"...therefore they had the spirit of prophecy, and the spirit of revelation, and when they taught, they taught with power and authority of God." (Book of Mormon | Alma 17:3)

And because of this power and authority they possessed, they -

"...had much success in bringing many to the knowledge of the truth; yea, by the power of their words..." (Book of Mormon | Alma 17:4)

This seemed to extend beyond their words only, but in leadership and example as the king's sheep were scattered, -

"...when Ammon saw this his heart was swollen within him with joy; for, said he, I will show forth my power unto these my fellow-servants, or the power which is in me, in restoring these flocks unto the king, that I may win the hearts of these my fellow-servants, that I may lead them to believe in my words." (Book of Mormon | Alma 17:29)

Preparation in searching the scriptures, prayer and fasting bring sufficient faith and power to bring success in our callings.