Start by listing your take-home income and all regular outgoings, including rent or mortgage, bills, food, travel, debts and subscriptions. Add less frequent costs, such as insurance, birthdays and car servicing, by estimating the yearly total and dividing it by 12. Set realistic amounts for savings, emergencies and discretionary spending, then compare your planned spending with your income and make adjustments if needed. Review your budget each month and use bank statements or a budgeting app to check whether your actual spending matches your plan.