Always pay on time. For the sake of emphasis, I'll repeat this one: Pay your bills on time! You can negotiate for favorable payment terms before you place an order, but once the order is placed, don't renege or attempt to change the rules. If you can't, call up your suppliers and tell them why and when you will pay. Don't play games with suppliers' cash. You'll be absolutely amazed at the goodwill and benefits you will earn by observing this simple rule.