-Build a Monastery once you reach the Castle age and collect as many Relics as possible. For every Relic you have, you will get one gold per second. For example, if you have five Relics, you will get five gold per second.
-Build a Market as far away from your allies as possible and build 20 to 30 Trade Carts. Send them to trade with your allies. After all of your Trade Carts are built, you will get plenty of gold. If you have 30 built, in about ten minutes you will have earned at least 10,000 gold.
-If you are in the Black Forest, get over 20 Villagers to chop Wood (30 would work better). After you have 20,000 Wood, sell it for tons of gold.
-Destroy your weakest opponent, then finish off everything except its market. Make sure that the path between your market and opponent's market is secure. Route at least twenty trade carts to trade and get tons of easy gold.