Getting paid in a down economy can be quite challenging, particularly for those businesses that have to extend credit to their customers. Maybe you, for instance? Even your best customers may find it difficult now to pay up in a timely manner, which means it's even more important for you to stay on top of your accounts receivable so you don't end up with a cash-flow crunch. "It's critical at these times to get a handle on accounts receivable," says Sean P. Melvin, an attorney, author and associate professor of business law at Elizabethtown College, in Pennsylvania. "It can really start to stack up quick."