As I'm writing the early portions of Enoch's Ghost, the second book in the Oracles of Fire series, I'm once again reminded of how difficult writing the beginning of a book, especially a sequel, can be. I have no idea how long it has been since a reader has finished the previous book, so I have to reintroduce characters, bring in reminders of the old storyline, and create a new stage for an engaging story. This problem isn't exclusive to sequels. In most first books there is an important backstory, so the story acts as a sequel to whatever set up the events of the first chapter.
Here are some of the potential pitfalls:
Contrived dialogue - This happens when the author makes characters say things to each other they normally wouldn't say in order to inform the reader of what's going on. It usually results in experienced readers grimacing at how stilted the characters are.
Backstory information dump - This usually occurs in narrative or interior monologue where the author informs the reader of what has happened in the past. I see it most often with a primary character thinking about what recently happened. This is similar to contrived dialogue. When it's done in narrative, it is usually boring, and it certainly slows down the story.
Sketchy characterization - In order to get the story going and hook the reader, the author jumps right into the action. Sure, it might be exciting, but if the characters aren't developed, the reader won't have an emotional investment in the outcome. The action won't evoke the kind of edge-of-your-seat response the author is looking for. This isn't as difficult to avoid in a sequel, because most readers will be familiar with the characters and only need a brief refresher.
Boring introduction - Sometimes an author will try to avoid the previous problem by introducing the characters slowly in their normal everyday environments. This develops characters well, but it can lose readers because the story just doesn't grab them. If a reader puts the book down, the author has lost. The author won't be there to scream, "at least get to chapter four! That's where it really gets moving!"
Are there other pitfalls? Please share them with me. Then, I'll try to relate some potential solutions.