D&C 88:77 And I give unto you a commandment that you shall teach one another the doctrine of the kingdom.
Sadly this scripture is not something we seem to particularly believe in.
First principle of teaching is that when the Holy Ghost manifests something to you to say, then go ahead and say it.
We have this funny idea that if the Holy Ghost plainly conveys something, but we can't think of a quote from general conference that says the same thing, then we should not say it. That is plain old ridiculous. If that was true, then there would be no reason for the Lord to give us the Holy Ghost. He could just give it to general conference speakers. That is all we would need.
In fact, not only is that ridiculous, it directly contradicts the scriptures.
D&C 42:14 And the Spirit shall be given unto you by the prayer of faith; and if ye receive not the Spirit ye shall not teach.
The scriptures require that we receive the spirit if we are to teach. Notice that "receive the Holy Ghost" is the commandment we get when we are given the Holy Ghost in the first place. It is the principle challenge of mortality. It is our quest here to discover how we need to live so that we have the Holy Ghost with us, and to continue to improve in ways that will increase that more and more. That is our path to returning to the presence of the Father. We are either standing in the presence of the Father, or we are not. There is not really a half way. But we can enjoy the Holy Ghost by degrees because he is a personage of spirit. This gives us a path back to the presence of God. When we do something that offends the Holy Ghost, we notice a difference. When we change our lives in ways that are pleasing to God, we find the Holy Ghost more in our lives. Those things that bring him most powerfully into our lives are the things we should seek after, as his influence can transform everything else.
And is there a point in having the Holy Ghost as a teacher except to teach by it?
D&C 50:17 Verily I say unto you, he that is ordained of me and sent forth to preach the word of truth by the Comforter, in the Spirit of truth, doth he preach it by the Spirit of truth or some other way?
18 And if it be by some other way it is not of God.
You will notice that this statement of scripture actually means that teaching rigidly by the manual or even by conference quotations, but silencing the whisperings of the Holy Ghost on what we ought to say is "not of God". That may make the hearts of those who cannot tolerate anything that isn't backed by quotation flutter with trepidation, but it is what God commanded. After all, does not the rest of the so called Christian world teach every week by the words of the prophets, but do so without the Holy Ghost? Do we think that if they can teach wrongly using old prophets without the Holy Ghost and that we cannot do so using modern ones while silencing him?
This trend among us to require a quotation behind everything seems to be a way that well intentioned individuals have taken up as a way to keep everyone in line. It is a tourniquet meant to keep out snake poison, with the end result that it cuts off the life blood and kills off the limb.
When God speaks, we must obey, and when he says that if we are to teach except by the Comforter then it is not of God, then we had better pay attention. He knows better than our best intentions.
So that is the first principle of teaching the gospel.