To effectively collect invoices on time, follow these basic steps: 1) Send invoices out and call clients after 7 days to confirm receipt and get a payment date, 2) Diarise to follow up 5 days after the payment date to check that payment was received, getting details of anyone who can resolve queries within 7 days, 3) If there are cash flow issues, request payment within 7 days and remind clients interest may be added for late payments beyond 30 days.