The big costs are usually easy to remember. The small ones are what surprise people: printing, transport, mobile data, snacks between classes and last-minute materials for a project.

Write down the money you expect to have and the fixed costs you cannot avoid. Divide what remains by week, not by month, so you can see a problem early. Leave a small amount unassigned for things that change.

Track spending in whatever format you will use consistently: a note on your phone, a spreadsheet or a paper page. Categories can be simple. The goal is to notice patterns, not to build a complicated accounting system.

Review the plan once a week. If one category is running high, adjust the next week before the balance becomes stressful. A budget is useful because it can change with real life.