Willem von Unnik offers a summation of ancient Greco-Roman historiography in ten rules:

  1. the choice of a noble subject
  2. the usefulness of the subject for its addresses
  3. independence of mind and absence of partiality
  4. good construction of the narrative, especially the beginning and the end
  5. an adequate collection of preparatory material
  6. selection and variety in the treatment of the information
  7. correct disposition and ordering of the account
  8. liveliness in the narration
  9. moderation in the topological details
  10. composition of speeches adapted to the orator and the rhetorical situation.

Source: Daniel Marguerat, The First Christian Historian.