Gather originals. Label with sticky notes on the backs of originals using a naming convention such as NER 0001, NER 0002, NER 0003. The letters NER are my initials. You should use your own. The reason for beginning with 0001 is that when the photos are scanned into the computer or original digital photos are placed in a folder/directory, the photos will stay in order that you have placed them. When you need to add a photo to the sequence use an increment such as NER 0001A, NER 0001B. This allows you to add two photos between NER 0001 and NER 0002.
Write captions for every picture. Each caption should tell a real story, not just be a label. People do not know your story. Tell the story behind the picture. Answer the question, "It is Aunt Betty Jo: so what or who cares?" The answer may be, "Aunt Betty Jo lived with my family when I was an infant and cared for me while my mother attended college, took care of the other children or worked at a job outside the home. Aunt Betty Jo went on to become a well-known author about child rearing. As a screaming colicky baby, I taught her everything she knew." The captions should use the same naming convention of NER 0001 so that the photos and caption maybe put together easily.
Prepare an outline with chapters and pictures within the chapters. Don't place the pictures into the word processing file, just have an idea which pictures go with which chapters.