Put together a comprehensive file on the accounting practices of each company you do business with. You do not want to have to duplicate your work later on another bill. When done well, accounts receivable management can make a big difference for any business.
Experience shows that the likelihood of collecting receivables decreases the older they get. A good way to improve cash flow is to make the entire company aware of the importance of accounts receivable, and to make collections. Having your sales staff informed on the status of an account can help as that account is their meal ticket. It behooves them to help collect a bill if their able. Once you've developed your receivable collecting practices stick with them.
For most companies, collecting accounts receivable is the largest single headache. No one really likes to do it. But past due accounts receivables can be one of the most damaging drains on your cash flow. And the further you get behind the more you compound the problem. If you haven't already then it's time to develop a sound process to track and collect accounts receivable. The life of your business may depend on it.