Pull last month's statements
Download or open your last 30 days of bank and credit card transactions. Include cash withdrawals and payment apps.
Sort into a few categories
Housing, utilities, groceries, transportation, insurance, debt payments, dining out, shopping, subscriptions, other. Ten or twelve categories are plenty; too many makes it hard to keep up.
Look for surprises
Most people find one or two categories much higher than they thought, often food delivery, subscriptions or small daily purchases. Don't judge it yet; just note it.
Do this today
Total last month's spending by category and mark the two that surprised you most.