Today I found a really well written article on that age-old issue of how to make money off of your design (or art) work.
When you are starting your career as a freelancer, it will be incredibly tempting to take on any work that comes along, no matter how unfairly companies are trying to compensate you. Remember that you are talented and that your talent has value and that ultimately it is up to you to determine how much people value your talent. ~ Jessica Hische
Read the article here: http://www.fastcodesign.com/3025992/how-much-should-you-charge-for-design-work-a-guide
Some other good resources on pricing (and ethics):