Sometimes people charge more than they are worth but I find that most professionals set their rates/fees too low. Women tend to be more competent and less confident therefore they are uncomfortable charging what they are really worth. Raise your rate a small amount and it is amazing how much more money you will make. I suggest that you raise your rate regularly or at least every couple of years.
Dan Ariely is a behavioral scientist at MIT and the author of Predictably Irrational: The Hidden Forces that Shape Our Decisions.