How can get more golds from my farms?

To get gold from a farm you need to attack with the Raider Class legion. The more gold you have available the more you will collect. and the less of other resources there are available the greater the percentage of gold that you collect will be.

Try attacking with a non class legion first to take rss and then use the class legions to try to get gold. Don't attack too many times though if you don't want to zero the city.