D&C 6

In a revelation to Olivery Cowdery, the Lord seems to summarize what all Latter-day saints should do -

"...keep my commandments, and seek to bring forth and establish the cause of Zion..." (Doctrine and Covenants | Section 6:6)

The cause of Zion would be the cause to live in such a manner where the people are -

"...of one heart and one mind, and dwelt in righteousness; and there was no poor among them."  (Pearl of Great Price | Moses 7:18)

And in doing so -

"Seek not for riches but for wisdom, and behold, the mysteries of God shall be unfolded unto you, and then shall you be made rich..."  (Doctrine and Covenants | Section 6:7)

For -

"...he that hath eternal life is rich."  (Doctrine and Covenants | Section 6:7)

And to establish the cause of Zion and learn wisdom -

"Say nothing but repentance unto this generation; keep my commandments, and assist to bring forth my work, according to my commandments, and you shall be blessed."  (Doctrine and Covenants | Section 6:9)

Obviously, to establish the cause of Zion would then be to teach true gospel doctrine, commandments, and principles, thus bringing many to repentance, or in other words, would be saying or leading to nothing but repentance.