Why must there be a "first"?
From the Book of Mormon:
"Yea, come unto Christ, and be perfected in him, and deny yourselves of all ungodliness; and if ye shall deny yourselves of all ungodliness and love God with all your might, mind and strength, then is his grace sufficient for you, that by his grace ye may be perfect in Christ; and if by the grace of God ye are perfect in Christ, ye can in nowise deny the power of God."
From this verse:
Who perfects us? Christ.
What does he expect from us? To deny all ungodliness and to love him with all of our might, mind and strength.
What happens if we do this? He perfects us (we don't perfect ourselves--by his grace, he perfects us).
What is the result? When we see his grace in our lives, and by such, we gain a sure testimony of his grace and power."
Faith and works are intertwined like the threads of a cloth. We have faith and obey and our faith is increased. Sometimes we struggle to believe, but we obey first and then our faith is increased.
Mar 9:24 And straightway the father of the child cried out, and said with tears, Lord, I believe; help thou mine unbelief.