How do you do your customer service billing?

There are countless online invoice options including FreshBooks and SimplyBill (http://freelanceswitch.com/money/7-online-invoicing-apps-for-freelancers/) but it is most important to establish a credit and collection policy for your customers. You should have some sort of qualification criteria (at least minimum required customer information) for extending credit or payments, defined repayment options (90 days same as cash, extended consecutive and equal terms with interest, etc.), appropriate legally binding documentation (quote and invoice, retail installment agreement, or promissory note), payment processing options (credit card, check by phone, etc.), and a default policy including appropriate escalation options (3rd party collections). Setting these rules and regulations ahead of time allows you to offer additional payment options at a courtesy for those who agree. For those who do not agree or for those older customers resisting the new procedure, you can still offer the same options you are offering now. Providing an incentive for the new process (i.e. paperless discount or pricing discount) will encourage those stragglers to catch up with the times.