Lotta bad book trailers out there. I've only seen one or two Christian Fiction ones that I liked. The biggest problem I have with them is they're too dang long. Some are also more focused on the praise music than the actual synopsis of the book. If you're thinking of developing a trailer to promote your book, here are some points to consider:
1. Keep it simple. Too many images can be confusing.
2. Don't overwhelm the reader with music. If it's there it should be in the background.
3. Keep it short. A trailer is a commerical of sorts. When was the last time you watched a 2 minute commerical? Commercials are under a minute.
4. Engage the viewer quickly. Most viewers click away from a trailer in the first 9 seconds. So you have to do something to reel them in and wow them before then, otherwise they won't watch.
5. Don't give away too much. It's a teaser. It's supposed to make the reader want to read more about the book.
6. Make sure there's an image of your book and your web address. The viewer should see them twice if you can manage it. Remember you're trying to make an impression on their memory.
Now here's an example of an excellent trailer I found visiting my friend Jessica's Blog. It's not Christian Fiction, but this preview is suitable for all ages.
Made me want to buy the book.
Readers tell me, has a trailer ever made you want to buy a book?