Pompei the Great: Try giving them more money and larger populations in some of their smaller cities from the start. Part of the problem they have in vanilla RTW is that as soon as the fighting starts they lose all their trade and have no money. They can't even trade with their own colonies because most of them are not developed enough.

WhiteProphecy: Have you installed the 1.3 patch? Did you start the game with the "Extended Greek Mod" icon on your desktop? When the game started did you see a big picture of Athens with "Extended Greek Mod" in large gold writing at the top?