Profit and cash are not the same thing, and the gap between them is where most small businesses get into trouble. You can invoice a record month and still be unable to pay yourself, because the money is sitting in someone else's bank account on thirty-day terms.
A thirteen-week cash flow forecast is the simplest tool that fixes this. Thirteen weeks is long enough to see a problem coming and short enough that you can actually estimate the numbers honestly.
Start with the cash you have today. Add the money you genuinely expect to receive week by week — not what you have invoiced, but what you expect to land. Then subtract everything going out: wages, rent, suppliers, VAT, tax, subscriptions, your own drawings.
The value is not in the accuracy. It is in the fact that a dip in week nine is visible in week one, when you still have options: chase early, delay a purchase, arrange a facility, or bring a payment plan forward.
Update it every Monday morning. Ten minutes a week is the whole commitment, and it is the single habit that most reliably separates owners who feel in control from owners who do not.