Talk to an attorney who specializes in debt collection. Attorneys can investigate whether a debt collector is breaking state or federal law and whether the claim is valid, defend you in court against a fraudulent lawsuit and respond to legal summons for you. You can get representation through a nonprofit legal aid clinic (where legal services are free), pro bono clinics at courthouses or private attorneys.
Next, estimate your monthly spending habits for other expenses such as gas, groceries and entertainment. Create a limit, based on your income, of what you can spend in each of the different categories of expenses. For example, if you tend to spend $400 a month on groceries, try to stick to $300 a month on groceries by making changes like buying generic brands, using coupons, and resisting impulse purchases.