As women, we chronically devalue ourselves. It's not an easy habit to break. I just did it, but it has taken years.
Breaking the Habit
First, in an odd way the economy has helped. Money is tight and low-balling is rampant. I've been going through so many job negotiations, it has forced me to reassess my own worth and stick by it.
Second, I was lucky enough to receive an epiphany: A good friend was giving me advice before a job interview recently, and she told me her income, as well as the salaries of some other colleagues in our industry. "That's your range," she said. "That's what your peers are earning, and that's what you should be earning."