Here's a great book for all of you illustrators, designers and/or artists.
Graphic Artists Guild Handbook: Pricing & Ethical Guidelines. The book is geared toward all visual arts professionals It has sample contracts and invoices for illustrators, designers, digital artwork, graphic design, etc. It has salary information and current industry rates as well. The prose deals with practical and legal advice for working as a professional in the graphic arts field. There's an interesting chapter with step by step processes on handeling an individual illustration/design job. Then we have detailed chapters on each of the specifics for print desginers, web/digital designers, illustrators, cartoonists, animators and surface design (textiles). It's really comprehensive and if you're working in this field, it's worth taking a look at. It's especially valuable if you've ever considered taking on freelance work—full time or in addition to current job.