Start with the last three months
Review bank and card statements before choosing categories. Look for the costs that repeat, the ones that arrive quarterly, and the small charges that are easy to underestimate when you plan from memory.
Give every dollar a job
Cover essential bills, then assign money to savings, debt repayment, flexible spending, and upcoming irregular costs. If the plan is short, change one assumption at a time rather than hiding the gap.
Review without judgment
Set a short monthly appointment to compare the plan with what happened. A budget is a feedback loop. Its job is to help you notice and choose, not to tell you whether you were good.