It is easy to loose your head when you get your first commission from someone really important. Don't forget to get the following information so that you don't panic. If in any doubt just ask. Avoid being left with any feeling of 'vagueness'.
1. Your brief
2. The fee
3. Format - size, dpi, colour
4. Contact details - make sure the client has yours ( keep your mobile by your side!). Make sure that you have their telephone number and email address.
5. Rough deadline
6. Final artwork deadline
7. Delivery details (type of file, emailed, posted, FTP site)
8. Keep communicating with the client, not too much so that you become annoying - you don't want them to panic. Just don't avoid them! Pretend that you are in control (even if you are in a flap) and fill them with confidence. It will all get done.