I cannot emphasize enough the importance of using style sheets if you are an editor. I created style sheets for myself before I even knew they were commonplace for editors. There is simply no other way to keep track of proper spellings, names, punctuation decisions, and other items that require consistency when you are editing. Before a manuscript is sent for final proofing, most publishers will require a style sheet. You might as well be the one to create it.
For my work, I use a two-level style sheet, one with formatting, punctuation, and spelling decisions in the top portion, and with an alphabetical list of words in the bottom portion. The alphabetical list allows me to quickly find and verify the spelling of any unusual or foreign words or proper names I find in the manuscript.
In the top portion, I write whether I’m editing for UK or US English (depends on the publisher), decisions about whether and when to spell out numbers (use words for one through ten, for example, and numerals for 11 and up), whether or not to use serial commas, how to cite sources in text and bibliography, punctuation (such as how to form an ellipse), and other items that must be consistent throughout the document.
With respect to names, I suggest that, even if you think the name is easily recognized, you write down the spelling, since authors sometimes change spellings in midstream. And always verify names against the bibliography, if one is included. (If there is a discrepancy, check Google to verify the author’s name.) I alphabetize by first name, last name (i.e., Richard Johanson) rather than by reverse order (i.e., Johanson, Richard), as you’d find the name in the Index.
Speaking of indexes, the style sheet is also an aid when you are creating an index, since you already have many of the topics and names listed. Using the style sheet, you can search for terms in the manuscript and record the page numbers (in a PDF file, prior to print).
Of course, initially, keeping a style sheet as you edit adds time to your endeavor, but in the long run, it saves time, so you don’t have to keep flipping back through the pages to verify how something is spelled. This is especially helpful with history books or books about foreign topics, where names are vital.
I strongly recommend that you create a style sheet for yourself and your client when you are editing a manuscript. Most publishers require one, and it’s a nice little bonus to give to your clients before they ask for it. Once you get the hang of using them, you’ll wonder how you ever did without them.