Have them pay in full, in advance, no exceptions. If they want to send a check, wait until it clears to start the job. That's how we handle out of town jobs. If it's an exceptionally large dollar amount, get the card number, and call the credit card company to verify the card.
After their second or third order, you can then discuss NET30 or Half-payment-up-Front options.
How do they put it?... "In God we trust, all others pay cash."
