1. Watch for new customers with a bad credit history. You can´t expect that a company or a person with a history of bouncing checks or paying their bills late will change their ways
2. Once you begin doing business with someone, make sure you stamp your invoices with the date that payment is due to you. Don´t rely on the customer to look at the invoice date and add 30 days -- or whatever your payment terms are -- to determine the pay date.
3. Offer discounts for early payment and add interest to late payments. A typical discount is two percent to three percent off the total if the bill is paid within 10 days of the invoice date. The maximum amount of interest that can be charged varies by state.