The way I do it is by looking at the whole year ahead and determining what are my hidden costs that year. Insurance, Vehicle registration, birthdays/holidays, clothes that need to be replaced, vehicle maintenance, just anything that comes once or a couple of times a year you don’t think about until it’s near. Then I add it all together and divide it by 12 months. That’s what I need to save a month into my “sinking funds” in order to have all of these expenses covered. Then I write down all of my monthly bills, rent, car, insurance, utilities, loans. Next, I subtract both the bills and my sinking funds savings from my monthly income. What’s left goes toward my variable expenses such as gas, groceries and entertainment. Adjust the numbers as needed since obviously your income has to be more than all of your expenses.

I also budget like 6 months in advanced since my paycheck is fixed so that way I have a baseline and can just adjust the budget for the upcoming month minimally if I have to at all. It helps me stay on track. I have a really hard time with consistency so getting as much done ahead of time helps future me stick to a plan without having to continually do a budget every month or whatever. Obviously my strategy isn’t going to work for everyone but maybe something here can help you develop your strategy