Personal and Professional Practice

Aggie pointed me to this website where it gives you useful advice about what to include on your invoice: http://businessofillustration.com/go-illustration-invoice/

Your name. Clients need to know who did the work.
Your contact info. So clients know where to send those sweet, sweet payments and contact you if there are any problems.
An invoice number. Something you and your clients can reference.
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.
An invoice date. So your clients and you know when the invoices were submitted and when they need to be paid.
The client’s information. Who the clients are and who commissioned the work.
A description of the work done. So your clients know what they’re actually being billed for.
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.
The total fee due. So your clients know how much to write on your checks.
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.

ive played around with having a image thumb box in the corner of the sheet - from discussions with Ben, he said this is good to remind the client what they are paying for, 

i decided to change the colour to a pale blue, i felt by using grey on a lot of my promo material, my practice came across boring and dull. 

as well as a invoice, ive created a acceptance of commission. this information was handed out to us in the AOI lecture which we were advised to use and give to future clients. so i have added my brand to the information and will be using it with future clients to make my practice more professional and legit and also make me feel more confident that i will be taken seriously.