Another way to boost your finances is to lower your troop maintenance sliders from 2.00 down to 1.40 or even down to 1.00 during peacetime. That saves around 10-25% of your troop upkeep costs. It takes a month or two to bring them back up to full strength (which happens at the end of the month), but most marches to the next province take almost a month of that time anyway, and you can generally engage weak rebel stacks successfully at 1.20 or 1.40 strength. In situations where peace is "questionable", I keep the maintenance slider to around 1.40 or 1.50, which is good enough to fight on short notice, but still not costing me the full amount for upkeep.
With hired advisors, make sure that the advisor's salary isn't costing you more than he is providing in benefits. An advisor who gives a small boost to Production, Tax, or Trade income in the early game is next to useless, because the hiring cost is more than the percentage increase will provide. The same advisor may be worth his weight in gold in the late game, when the income levels are far greater, and a couple of percent increase is enormous compared to the paltry salary of the advisor. Early on, I'm primarily looking for advisors who provide an increase in research, which will put my country in the position to benefit from those income boosting advisors sooner. Other advisors provide ZERO benefit except under specific circumstances: an Artist is ONLY useful if you've got stability lower than +3, and a Banker is ONLY useful if you've gone into debt, and Theologians aren't any help if all your provinces are of your national faith (aside from the ability to enact particular laws which require a certain type of advisor). Any other time, they're costing you money for no benefit.
