The main problem I've had with the game is that star rating becomes too difficult to come by later in the game. For instance I transfered to a new team and didn't get the ball most of the game and therefore lost rating with everyone even though I made every pass and goal/assist because I only had like 4 opportunities. Basically, there should be some way (difficulty modifier or something) that allows you to still get rating for your team, boss and fans for each game after a couple levels. Other than that the game was really good.
The problem with this game is for the first 4-5 levels all you have to do is hit assault and watch your units dominate. Level 2 or 3 requires a second unit, and 4 a second hero. I can get infinite gold by clicking assault and playing another game while I wait.
Also for Athena make sure you have the Necromancer's Bow. To get it just get around 16 billion (or more) points, buy the ultimate bow and than beat Eragoth.
To beat Athena is close to 100, it depends how well you combo and if you level yourself halfway through on purpose. As for Zakum just keep buying fortune cookies until you get one that says you are about to have a really bad day.