In addition to that:
-Build your trade network. Link all of your cities via roads or rivers, and when possible, build land routes to neighboring nations as well. Much of the trade is automated in Civ IV, but it only happens when you have open trade routes.
-Work your civics. Try to find a good balance which gives you the perks you want while minimizing your costs.
-Build wonders which can help you create great merchants; when one is born, use him to conduct a trade mission to a far off, foreign city--the bigger & farther, the better.
-Once your cities start growing, make sure to build your markets & banks, as well as trade generating improvements like harbors and airports. Especially if you're playing on a normal or lager sized world, take advantage of Marsailles and The Forbidden Palace when you can--those will help to cut down on your city maintenance costs.
-Finally, don't build too much, especially in the early game. Depending on your difficulty setting, having too large a standing army or too many buildings in small cities can be a big drain on your treasury.