This is the outline that I would follow if I were teaching the lesson.

I have a personal theory that every lesson is, at root, about at least one member of the Godhead. Some focus more on Christ, some focus more on Heavenly Father, and some focus more on the Holy Ghost. By my interpretation the star of this lesson is the Holy Ghost. Right out of the gate the manual points out that

“True to His [where His=Jesus’] word, He continued to guide them from heaven. He sent the Holy Ghost to be a comforter and a revelator to them.”

The church of Christ was only able to exist without him on the earth because of the Holy Ghost. And I would assert that the apostasy is ultimately caused by the loss of the Holy Ghost.

The manual lists 6 characteristics of the Church of Christ in former times

1. Revelation
2. Authority
3. The Church organization
4. First Principles and Ordinances
5. Work for the dead
6. Spiritual Gifts

1. Revelation See Matthew 16:16-18 which reads

16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God.
17 And Jesus answered and said unto him, Blessed art thou, Simon Bar-jona: for flesh and blood hath not brevealed it unto thee, but my Father which is in heaven.

Peter is sitting there with Christ himself- and Christ is calling Peter blessed for not listening to flesh and blood (which at this point included Christ) but for listening to personal revelation from the Holy Ghost as directed by God the Father.
See also John 14:26

26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.

Prophets are certainly called of God, but their words are useless until we confirm their truth to ourselves through personal revelation. Even in Moses time it was clear that the goal was not just a nation willing to follow a priest or a prophet, but rather “And ye shall be unto me a kingdom of priests, and an holy nation.” (Ex 19:6) Certainly it is necessary for those leading the church to recieve revelation, but I think the scriptures make it clear that every member should be seeking revelation from the Holy Ghost.

2. Authority– See Luke 9:1-2

“1 Then he called his twelve disciples together, and gave them power and authority over all devils, and to cure diseases.
2 And he sent them to preach the kingdom of God, and to heal the sick.”

Christ not only gave the apostles authority, but he also gave them the ability and a way to pass on that authority to others. A realated question I don’t have neat answer to is: “Why are ordinances performed without authority ineffective? What about when someone with authority may not be strictly worthy? How or why are those two situations different?”

3. Organization: See Eph 4: 11-13

11 And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers;
12 For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ:
13 Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:

From this I see that there is different jobs for everyone to do, but that the goals listed in verse 13 are unity, and for each of us to be more like Christ. Our different tasks are not an injunction for us to withdraw into our specialities (which is very tempting to do), but for us all to actively develop any and all Christlike qualities.

4. Ordinances See Acts 19:1-6

1 And it came to pass, that, while Apollos was at Corinth, Paul having passed through the upper coasts came to Ephesus: and finding certain disciples,
2 He said unto them, Have ye received the Holy Ghost since ye believed? And they said unto him, We have not so much as heard whether there be any Holy Ghost.
3 And he said unto them, Unto what then were ye baptized? And they said, Unto John’s baptism.
4 Then said Paul, John verily baptized with the baptism of repentance, saying unto the people, that they should believe on him which should come after him, that is, on Christ Jesus.
5 When they heard this, they were baptized in the name of the Lord Jesus.
6 And when Paul had laid his hands upon them, the Holy Ghost came on them; and they spake with tongues, and prophesied.

Summary: How could Paul tell that these members were baptized incorrectly? They didn’t have the Holy Ghost. How can you tell when ordinances are done properly- they will have the Holy Ghost. The Gift of the Holy Ghost is among the best things we get out of those first principles and ordinances of the Gospel. Why do we need the Holy Ghost? So we can receive revelation.

5. Ordinances for the Dead– of all the things the modern church does that get weird looks from other denominations this is one that I find odd. It has plenty of biblical support (1 Peter 3:18-20, 4:6 and 1 Cor 15:29) and I don’t see how a just God could fail to provide an opportunity to everyone to learn of Christ before being given the choice to accept or reject ordinances.

6: Spiritual Gifts
From the manual “All faithful members of the Church were entitled to receive gifts of the spirit.” Note that it says all. Very often I see women sidelining themselves and not even attempting to make use of any of the gifts of the spirit, thinking that many things are the strict purview of Priesthood holders. Reminding ourselves that all members, including women, are entitled to gifts of the spirit (as found in 1 Cor 12:4-11, Moroni 10:8-18, D&C 46:8-29) will allow us to be more receptive when the Holy Ghost may prompt us to do something.
Sister Dew said :

“It is vital that we, the sisters of Relief Society, learn to hear the voice of the Lord. Yet I worry that too often we fail to seek the guidance of the Spirit. Perhaps we don’t know how and haven’t made it a priority to learn. Or we’re so aware of our personal failings that we don’t feel worthy, don’t really believe the Lord will talk to us, and therefore don’t seek revelation. “

Apostasy– The manual lists a lot of things that went wrong and caused the original church to fall apart, but I think it overlooks the most basic one: The Holy Ghost. If the members and leaders of the early church had been seeking and heeding the guidance of the Holy Ghost then they could have avoided all those wrong turns that destroyed the original church. And this is still true on a personal level- that our relationship to Christ and belief in His Gospel is dependent on our reliance upon the Holy Ghost.

Note: This lesson was originally written for the Relief Society audience in 2010-2011, when the Gospel Principles manual was temporarily used as curriculum for Relief Society, Elders Quorum and High Priest classes. The lesson may require adaptation for Gospel Principles classes, which are mixed gender and primarily serve new members and investigators of the church.