I. Your Greek male characters must be philosophers, pederasts or homosexuals (but see Rule V). NB re Spartans: for 'philosophers' read 'stoics'. Your Greek females must be priestesses, nymph(omaniac)s or poets of the Sapphic persuasion. NB Spartan women should be wives/mothers/daughters who invariably instruct their menfolk to return home from war with their shields or on them.
II. Your Greek characters must always be witty, eloquent, learned and wise. (But see Rule X subsection v). Your Romans, though intellectual pygmies with no sense of humour or irony, can be relied upon to use the ablative absolute correctly when quoting Virgil or Cicero (which they must do at least once during any novel in which they appear).
III. Civilian Romans of either sex must (except for your Hero/Heroine) be any combination of decadent, fat, sleazy, grasping, politically corrupt or sexually depraved. They must be either bald (male) or afflicted with a high-rise hairdo (female). They must wear togas in all circumstances, however impractical (even the women). They must always consume (preferably to excess) stuffed dormice and braised lark’s tongues at least once during any novel in which they appear.
IV. Commissioned officers in the Roman Army must be anal-retentive control freaks with arrested libidos that can only be jump-started by comely Barbarian captive maidens. Such officers must always say, “The Roman Army is the greatest war machine the world has ever known” at least once during any novel in which they appear.
V. All Greek soldiers are Noble Heroes. All Barbarian warriors are Impassioned-But-Hopelessly-Disorganised Heroes. All Roman legionaries are Plundering (or Blundering) Rapists. The Plundering (or Blundering) Rapists must always win. (There’s a lesson here somewhere).
VI. Barbarians must always be portrayed as politically-correct Noble Savages, especially if Celtic. They must embrace sexual equality and be in total harmony with Nature and the Mystic Elements. They must always lose the battles but win the moral high ground (whatever that is), especially against The Greatest War Machine The World Has Ever Known. That’s probably the aforementioned lesson (see Rule V).
VII. In battle against Greeks and Romans, Barbarian chariots always have scythes on their wheels, never mind that blades would do more damage to themselves than to the enemy. Britons must paint themselves with designer woad before going into battle. This is not optional.
VIII. Your Hero must find slavery, crucifixion and gladiatorial combat Morally Repugnant.
IX. Despite the evidence of Cicero, Pliny the Younger and various Roman tombstones, slaves are always ill-treated except of course by your Hero (see Rule VIII). Revolting slaves are invariably idealistic, selfless proto-Communists who want to change the world. They are never just people who want to go back where they came from.
X. Miscellaneous Rules
i. Roman roads never have bends in them. Therefore they must always be described as “arrow-straight” (NB for the sake of variation, “spear-straight” is an acceptable alternative).
ii. Christians are always Persecuted, usually by lions.
iii. Jews are invariably Stiff-Necked. Sometimes they are also Biblical (or Apocryphal).
iv. Druids are usually to be found looming out of Celtic mists to incite rebellion. Some of them are women.
v. All doctors are both quacks and Greeks.
vi. All Roman emperors are devious psychopaths with speech impediments who marry their sisters, appoint their horses to the Senate, fiddle while Rome burns and die from eating poisoned mushrooms (or dormice or larks’ tongues - see Rule III).