The indexer should decide definitely in his mind just what his
procedure is to be before actually beginning work. At first, it is well
to make the index too full rather than the reverse, as it is easier to
cut out than to fill in. Most important of all, he must be sure that
the matter to be indexed is clearly understood before he attempts to
transcribe the idea. The character of the book to be indexed must be
carefully considered, taking into account the class of people who will
probably consult it, and the lines on which they will probably seek
information.
Judgment is required in deciding whether it is wise to choose the
exact words of the author or to condense the idea into other words.
In technical books, the exact wording is sometimes essential, but
otherwise it is more important to express the _idea_ than the exact
terms in which it is expressed.
Always prefer simple words and expressions to those which are unusual
and cumbersome.
Omit every unessential word.
When the book being indexed is one written upon a specific subject,
this main subject should not be indexed unless necessary to indicate
some reference for which a searcher would look. Ordinarily, the
Contents covers this point rather than the Index.
Bear in mind particularly the two extremes: the importance of
including every reference necessary to enable the searcher to find what
he wishes without delay or confusion, the mistake of overloading the
index with useless entries.
Use ink, as pencil entries often become illegible.
Write plainly, and do not try to economize space in preparing the copy.