What also makes for a good game is - when you have to much money - spending money on your other side of the map friend ,
This is what I mean;
when I was playing the Romans - rolling in cash - I decided to help the Seleucid Empire versus the Egyptians ( Who I really hate.. ) so I sent in a diplomat and gave them all the money I had left when I was about to end my turn.

The fun part is that you cna now hope for great battles if you - in the end game - decide to end your alliance , an alliance isn't necessary , just makes it a little more fun and real , in my opinion