Use 70 or 72 as your fill column.
Longer lines are hard to read.
Include a copyright notice and copying permissions. Write many index entries, in different ways. Although it is easiest to write index entries as you write the body of the text, some people prefer to write entries afterwards. In either case, write an entry before the paragraph to which it applies. This way, an index entry points to the first page of a paragraph that is split across pages.