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.
The client's contact information -Now you'll want to specify who the invoice is being made out to. Include the recipient's name, address, phone number and any other info below the invoice header.