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.
If you're a company that plans to extend credit to your customers, you'll have to get familiar with invoice generation. The invoice is a bill to another business that lists the total amount due along with a breakdown of the items purchased. When it's time to generate invoices to send to your customers, you can make the process simpler by using templates in Microsoft Excel.