When we assign talks, we give them a slip of paper with the theme and scripture on it (and an explanation that they can choose a different topic if they want) and these four steps:  

1. Read a scripture
2. Explain the meaning
3. Use a personal story to expound
4. Bear testimony of the truth of the principle.

These were given at a regional training session by Sister Matsamori, who is now a member of the General Primary Presidency.