My indexing training is based on the rules according to the Chicago Manual of Style. Many house styles vary somewhat from Chicago. Working from your written guidelines or a sample index, I can provide a finished index that conforms to your style.
Indented style indexes are generally easier to read. Each sub-entry begins on a new line. A run-in style index will save space if that is an issue. In this style, sub-entries follow one another in a paragraph style, separated by semicolons.
Alphabetical arrangement of entries can be letter-by-letter or word-by-word. If your normal house style is letter-by-letter but you have an index with a large number of names or related phrases, it might be better to consider a word-by-word arrangement. With the indexing software I use, indexes can easily be sorted either way and it is a simple matter to change from one to the other
Capitalization rules vary widely. If you don’t have a specific house style, we can discuss what might be most suitable for your index.
The format and placement of cross references is also important. Some run off the main headings. Some are formatted as the last sub-entry to provide the reader with additional information. Your house style can be accommodated in this area, too.