Be transparent – Your client wants to know where their money is going, so don't hide or be too general with line items on your invoices, and be prepared to show receipts. Otherwise, they'll wonder if you're padding the bill. Be specific. For example, instead of listing "materials" as a single expense, list each one on its own line, such as: paint, nails, plywood, etc.
Next, you need to specify your payment options — whether you prefer to be paid with cash, a check, a credit card or a service like PayPal. Some companies will offer direct deposit, if you do regular work for them, but more than likely you'll have to send an invoice to request payment every time you complete a project.