When you move to a new city it takes a while to know your way around. The process seems to begin with finding landmarks, and then it becomes a quest to join the dots. We need to help people do the same in their Bibles. They need to know the high points. Then they need to see how they fit together and connect. Now for my third suggestion:
3. Give them a tour. Why not take a series of sermons and be more overt. Instead of just making passing references to landmarks and connections, make that the goal of the series. I’m toying with just such a series. But I’m not sure which way to go. Here are some ideas “off the top” . . .
A. Ten key passages. My friend preached a series this way last year. I can’t remember his ten passages, but how about something like: Genesis 1, Genesis 3, Genesis 12. Perhaps Exodus 19, 2Samuel 7, Isaiah 42. Why not Jeremiah 31, John 3, Ephesians 2 and Revelation 21?
B. Eight key events. How about: creation, fall, promise, Sinai, exile, incarnation, passion, return of Christ? That could work. I’d want to stick to one or two key passages for each (perhaps the main one and then a commentary on it from elsewhere?)
C. Seven people you need to know. Perhaps Adam, Abram, Moses, David, Jeremiah, Jesus and Paul.
D. Seven chunks of Bible text. The books of Moses, the history books of Israel, the wisdom books, the prophet’s books, the books of Jesus’ passion, the history book of the early church, and the books of the apostles.
Other approaches that would give an effective introductory tour of the Bible? Feel free to make your suggestions…
Biblical Preaching 
I think you are right on track and think that this type of overview preaching is needed in our congregations. I recently had a conversation with a friend about this and came up with some of the same ideas. It was in the midst of our discussion that we thought of another way to do an overview found in the book of Matthew 1:17 where he summarizes the genealogy of Jesus with three eras: From Abraham to David, from David to the deportation and from the deportation to Messiah.
We thought that is would be very important for people to understand the big story of God’s working in redemptive history starting with the Patriarchal period leading God’s deliverance of His people in the Exodus, to Israel as a united Kingdom under David. From a united Israel through the divided Kingdom and their disobedience leading to their exile and deportation and then the return and anticipation of the Messianic hope which has come in the person of Jesus. It is these big mountain tops from which the terrain of redemptive history can be viewed that we thought would be very helpful for many.
Only three of ten “key passages” for the whole New Testament? As many as for Genesis alone?
It was “off the top,” but Genesis is critical. I could see chapter 1 being assimilated into 3, but 12 is also critical. Maybe I’d combine 1 into 3 and add Acts 2.
Sounds fair to me, people are generally much more familiar with the new testament anyway, and if you handled the big events in the old testament well you would effectively set the scene for the NT events and thus they wouldn’t need as much time to make clear.
Of course in the broader context of Church life there are loads of essential NT passages which have a huge impact on how we understand the rest of the Bible, but in the context which Peter is talking about it’s probably fair to say that there are more key events in the OT.
I like the events approach very much, though. Strong on narrative, which always helps to keep people’s attention, and really good for getting the whole sweep of the Bible story.