My formula on saving money is (income - savings = expenses) you can put the 25% of your income to your bank account. That's the best tip for me to save money.
My professor told me that in order to save money, you have to save some before you budget your remaining money for your monthly bills, because if what you are going to do is the opposite, budgeting first your money for your bills before saving some, then you can't save enough money for your needs in life.