Go to a permament war with a remote city state. You can train your soilders at their walls. Pick up cover and healing for the melee troops and logistics for the archers. Then you don't have to have such a big attacking force, you'll save money. Later make trade routes with city states and liberated non-capitals. Also save great artists for wartime, the golden age can solve your money problems.
Also Honor policies and Statue of Zeus is quite obvius I think.