What Should Go on an Illustration Invoice?

http://businessofillustration.com/go-illustration-invoice/

On this website I found a page on the important things to include on an invoice. I've never made one before so I found this helpful. I took not of the things to include. Invoices don't need to too fancy but simple and to the point. I can add some design element to make it look more interesting and personal but it shouldn't be a work of art that I spend too much time on.

1. Your name. Clients need to know who did the work.
2. Your contact info. So clients know where to send those sweet, sweet payments and contact you if there are any problems.
3. An invoice number. Something you and your clients can reference.
4. The client’s PO number (only if applicable). Some clients will give you purchase order numbers. For ones that do, you should include them on your invoices.
5. An invoice date. So your clients and you know when the invoices were submitted and when they need to be paid.
6. The client’s information. Who the clients are and who commissioned the work.
7. A description of the work done. So your clients know what they’re actually being billed for.
8. A tax ID number. For government purposes. Because you don’t want every client you work with to have your social security number (invoices go through a lot of hands), I’d recommend getting an EIN number which can be used instead.
9. The total fee due. So your clients know how much to write on your checks.
10. Payment terms. So your clients know when payment is expected to be received by and what happens if those payments are late. Standard is 30 days upon receipt.