I would suggest to build up well defended fortresses (if possible on mountains etc) like hell at the border, hopefully they can't get through. Use lots of bombers & arty and don't bother to attack their cities (have stacks of doom running around - avoid *single* skirmish like worker capturing etc as there's no tactic or strategic value in doing so). You'd better raze captured cities (you don't care for reputation anymore - and it simply fits to your conquest plans), thus you need not to put defense there and need not fear culture flips; overall you will decrease their production capacities. One or another *well* placed city might not be razed in order to serve as new bomber base.
Be sure to deploy enough air sup. units at the border. You may put your economy on mobilization status and switch your government (I'd prefer communism in modern times - but other forms besides democracy might also do well).
The ai tends to avoid assaults against adamantly defended spots/stacks. If you keep your forces together, Persia might not get to any serious initiative at all (note: I don't know if ais use nukes in the field though). Be sure to end up a turn with your stuff placed on tiles with def. bonus, if possible. Protect your MA/arty stacks with lots of MI.
If it fits to map's geography, you also might put an aim on cutting off resources first. Ah, watch the seas: you don't want to have a backdoor invasion.
Yeah, and good luck, kick Xerxes butt (Comrade Grille of Egypt will do , too, in his current game tonite)!
