Phase 1: Gather Your Numbers

Pull all income sourcesList every paycheck, side income, and benefit; consumer.gov's process starts by having you gather your bills and pay stubs before anything else.
Collect a full month of bills and receiptsPull statements, recurring bills, and pay stubs so nothing gets missed when you list expenses.
List every bill and expense with its amountMake a list of your bills and other expenses and the amounts, including irregular ones like annual insurance premiums or car repairs.
Separate fixed costs from variable spendingGroup rent/mortgage, loan payments, and insurance apart from groceries, gas, and entertainment; this makes it obvious where you have flexibility.
Include irregular household income if has irregular incomeIf you or a partner freelance or earn commission, average the last 3–6 months rather than using one high or low month.

Phase 2: Build the Working Budget

Subtract total expenses from total monthly incomeSubtract your monthly bills and expenses from how much money you make in a month; this number should be more than zero. If it isn't, you're spending more than you earn.
Flag any month where spending exceeds incomeA negative result signals you must cut spending or increase income before committing to the plan, since if the number is less than zero, you're spending more money than you make.
Choose an allocation framework, e.g. 50/30/20The 50-30-20 rule targets 50% of after-tax income toward necessities, 30% toward things you don't need but make life nicer, and the final 20% toward paying down debt and/or adding to savings; treat it as a starting guideline, not a strict formula.
Base percentage splits on take-home payThe 50/30/20 budget rule is based on your take home pay — the amount you divide is your total income minus taxes.
Identify categories you can trimCompare your list against the framework and look for things in your budget you can change.
Build a working budget worksheetPull income, bill due-dates, and spending into one document/tool so you can see the full picture at a glance, as recommended once you've identified all of your income sources and started tracking your spending and when your bills are due.

Set an emergency fund targetBase the goal on your own risk, since the amount you need in an emergency savings fund depends on your situation — think about the most common kind of unexpected expenses you've had in the past and how much they cost.
Start the emergency fund even if smallEven a small amount can provide some financial security if you're living paycheck to paycheck.
Automate a fixed transfer to savingsTreat it like a bill so debt paydown and savings actually get funded under the "20%" portion of the plan rather than being whatever's left over.
Set a specific, motivating savings goalHaving a specific goal for your savings can help you stay motivated; establishing your emergency fund may be the achievable goal that helps you stay on track early on.
Prioritize high-interest debt payoff within the 20% if has high interest debtIf you carry credit-card or other high-interest debt, direct most of this bucket there before building savings past a small starter fund.

Track spending in real time daily or weeklyCreate a way that's easy for you to track income and spending in real time, whether that's a daily journal or putting receipts in a folder that you review at the end of each week.
Re-check the budget monthlyA budget is something you use every month; at the beginning of the month, make a plan for how you'll spend your money that month, then compare against actual results.
Update the budget after any income or spending changeBe sure to update your budget if you experience a change in employment or your spending habits, since an outdated budget can mask a shortfall.
Expect the habit to take timeChanging your money habits won't happen overnight; making and sticking with a budget takes effort, so build in a few months of adjustment before judging results.
Pick a tool that matches your habits, not someone else'sCreate a tool that works for you, be realistic, and start looking at your finances one month at a time rather than copying a system you won't maintain.