For all this, the necessary first principles and ordinances of the gospel (aka Plan of Salvation, or Plan of Happiness) are...

• ...are first, faith in the Lord Jesus Christ (we can learn about Him and why to trust Him),
• ...second, repentance (we can and must change our ways to reflect His teachings; the missionaries can help),
• ...third, baptism by immersion for the remission of sins (by the proper authority),
• ...and fourth, the laying on of hands, for the gift of the Holy Ghost.
• The Articles of Faith of the Church of Jesus Christ of Latter-day Saints [a couple of pages: very good, worth reading/considering the whole]
  

  "4 We believe that the first principles and ordinances of the Gospel are: first, Faith in the Lord Jesus Christ; second, Repentance; third, Baptism by immersion for the remission of sins; fourth, Laying on of hands for the gift of the Holy Ghost."

• The very most essential things: how to find truth, peace in this life, and Eternal life in the world to come: what makes everything else work and have purpose
• MANY RESOURCES: search by topics, at www.churchofjesuschrist.org (magnifying glass icon): includes a very good 12-step program, & much, much more. (main)