Setting budgets has no effect at all. The feature hasn't been implemented. All the budget does is reflect your projected income and expenditure based on existing data.
Maintaining high employment is the best way to increase income, as well as encouraging CEO corps to build or relocate, as CEO corps pay additional costs to the country, as well as income tax based on salaries. If you have your own CEO, increasing salaries in the corps in your own countries will mean that your CEO will suffer, but the country will benefit.
Schools cost money to run, but result in more professionals. Low Health index results in fewer births and more early deaths, therefore fewer workers, but too high and social security costs will go up with a higher number of pensioners. Aim to achieve a balance ... as with everything in this game.
Hugs and respect
Jo