I want to start laying out a book – but know that I will need to find more photos from my husband’s laptop, capture some stills from iMovie, etc. before I complete the project. Before I start, I want to make sure I can save my work and retrieve it when I’m ready to start another session.
— Marilyn Murphy
When you start a photo book in iPhoto it will appear on the left under "Keepsakes." It saves as you work, automatically. You can return to work on it at any time.
Try a sample photo book to get the feel for it before you begin your big project. It is a good idea to familiarize yourself with the way the tools work so you can know what is possible even before you start planning. Then you will see.