Step 1: Total your monthly income
Add up your take-home pay across all sources, after tax. If your income varies, use the lowest realistic month from the last 12 as your starting figure. You can always reallocate windfalls later.
Step 2: List your fixed obligations
Rent or mortgage, utilities, insurance premiums, subscriptions, minimum debt payments, and any standing transfers. These are the payments that come whether or not you remember to make them.
Step 3: Set variable category caps
Groceries, dining out, transportation, personal spending, entertainment. Each gets a number based on the last three months of activity, with a small reduction in any category where you want to cut. The cap is a soft ceiling. If you go over in groceries, you have to make it up somewhere else, not pretend it never happened.
Step 4: Assign every remaining dollar
What is left after fixed and variable categories is your surplus. Send it to its job: extra debt payment, emergency fund, savings for a goal, or your next month's buffer. Income minus everything should equal zero. If it does not, you have not finished the budget.