Once you’ve locked in your pricing, sending invoices is arguably the most fun part of running your own business (and the easiest). An invoice is just a bill you send to another company for products sold or services rendered. On an invoice, all charges *should* be itemized, so whoever you’re billing knows where the total amount owed came from (exactly like the bill you get at a restaurant after eating out). Even if you’re in a service industry, itemizing out the different aspects of your service can help eliminate confusion (and might actually allow you to justify charging more). Check out a simple sample invoice here.
The way you structure your invoice is really up to your preference, but I like to include a section at the bottom to include any reimbursements. Historically, I’ve had clients ask my company to pay for something for whatever reason (sometimes it’s just easier), and just have me tack it on the invoice to be reimbursed later. Obviously reimbursements should always be discussed with the company you’re billing ahead of time.