Making money requires a bit of good planning. Getting a big army is easy, it's maintaining it that's the problem. I'd recommend getting a TON of enterprises everywhere in cities that your faction owns. If you do a bit of research, seeing what raw materials are more abundant in what town you're making the enterprise and then making an enterprise which goes hand in hand with the raw materials, you can make some good money. Along with this, you'll want to make sure to have one of your companions based off as a Trader, so that way, they can give you some good trading info and with that, you can transport the goods you get to another city and sell them. Doing this, I managed to have enough money per week to completely pay off a company of 150+ troops, as well as still gaining money.
Also, you should think about trying to win a few tournaments, but wait until you're more experienced before betting heavily on yourself.