When you do Mercenary missions that give you a specific amount of money, always go for the highest amount. For example, the "Snow Tigers" mission will give you 1,600 gold. You can get plenty of gold in that mission by helping the other generals that are getting attacked by other armies, but do not attack the Snow Tigers just yet. Have the Snow Tigers be the final thing to fight. Repeat this mission as many times as desired. Note: When you do these missions repeatedly to get more money, and you have to end your turn, the other generals in the other countries level up more than you do, and you can get defeated easier.