Q. How does one go about preparing an index? Any web page I can go to?
A. I typed “preparing an index Chicago” (without the quotation marks) into Google and found many sites that offer guidelines. Here are a couple:
http://www.psupress.org/author/indexing_guidelines.pdf (Penn State University Press, “For Authors: Index Preparation”)
http://www.nebraskapress.unl.edu/pages/Manu_Prep/IndexPreparation.pdf (University of Nebraska Press, “Publishing with the Press: Preparing Your Index”)
And of course CMOS 16, chapter 16, tells you all you need to know and more.