An index is an important part of an academic book, but one which is frequently overlooked, particularly in terms of scheduling time and allotting funds for it. If you’re interested in an index for your monograph, it is useful to consider it early in the editing process; in some cases, word lists that are compiled while editing can be used in the indexing process. Determining what type of index or indexes naturally depends on the work itself. Many academic works are enhanced by several indexes: one for people and places, subjects and terms, and one for scriptural citations.
I have worked on a number of indexes; sometimes my role takes the form of editing indexes compiled by the author or translator, sometimes I compile the index independently, and sometimes I work in coordination with the author or translator. I have compiled indexes manually, transferring them to Word documents, and also created indexes in Indesign files (embedding/tagging the terms).
Regardless of the software I use, each index is created individually, by considering the nature of the work and the reader. I do not believe that indexes of academic works that are produced automatically are nearly as useful to the reader as those which are compiled by an indexer with a thorough understanding of the work and a concern for the ways a reader will utilize the index and the book. For example, not all instances of a term or name are necessarily relevant; the indexer, sometimes in coordination with the author, makes the determinations of which to include and which to omit, saving the reader from wild goose chases. The inclusion of well-thought out cross references can be quite useful to readers who may not immediately see the relation between two terms or topics. An indexer who has read the book carefully many times (as editors inevitably do) can make sure these cross references serve as a guide to the reader, enabling him to find just the reference he needs.