In my first campaign as the Brutii (M/VH - I was very familiar with the battle game and could take the challenge, but was still a little unfamiliar with the campaign games subtleties) I found that with enough well placed temples of Mercury, the entirety of Greece and the Aegean region, Rhodes and Large Chunks of Turkey etc under my control, that my bank account quickly grew to between 500,000 and 600,000 denari. This was accomplished by before 220 BC, and allowed me to seize Rome, Sicily and the entirety of the Italian mainland in the two years between 199bc and 197bc.... all told this only cost me around 100,000 denari in lost trade (i.e. my bank account only dropped to 420,000 at its lowest point). One way of putting such alot of money to use is to start building forts and garrisoning them with semi large armies, so when the time comes to seize Rome you can safely divert all of your experienced armies towards the other factions. I never really wanted to give handouts etc to other factions (that moneys mine...... ALL MINE) as I wanted to have enough money to seize Rome without any difficulties, and feel secure when I can spend in excess of 50,000 on construction for a single city in a single turn and only see the slightest dent in my bank balance...