All books will be a much better book with an index (exceptions are novels or children’s books). You are very familiar with what is in your book and where it is, but everyone else doesn’t have this knowledge. An index will aid the reader and researcher to find exactly what they are looking for and know for sure if the information they are looking for is in your book.
There are a small number of family histories that can use automatically generated indexes. Most histories will need to be manually indexed. One of the main problems with any kind of automatic indexing is that we don’t have a person’s name listed exactly the same way each time. For example, one time we may list someone by their full name, the next instance my just list their first name, and then we may have another story that just uses their nickname. Only a manual index will be able to have all three of these listed correctly for the same person.
Most people are familiar with the index card method of indexing a book, and that way still works, but I have a little easier way to manually create an index. As you are working on the book and typing it up, make a new file called “index” and begin listing all of the names that you would like included (listed surname first). Include key place names (towns, counties), important events (world wars, accidents), as well as people in your index. For female members or instances where the family name changed significantly in spelling, consider using cross-references to maiden and married names or alternate spellings used by the same individual.
When you are finished writing, proofreading, and editing the book and it is all ready for the publisher, have your word processor alphabetize the list of names that you have typed. Now as you go through the book for the last proofreading (usually from the printer’s proof) add the page numbers for each person and your index is done. Pretty slick.
Some people judge a book by its cover. Most genealogists judge a book by its index.
If you would like to look further into using an indexing program, here are some good links for you to find more about them.
Some indexing programs you can buy are listed on this site: http://www.anindexer.com/about/sw/swindex.html
Here are two articles about the limitations and disadvantages to using an automatic indexing program: http://www.backwordsindexing.com/Comp.html
Email questions and I’d be happy to help.