"Being a bitch doesn't make you a strong character."
Via the always impeccable Yahtzee on Escapist Magazine:
There are plenty of examples of this kind of bad female characterization. Lara Croft, the classic feminist hate figure, and her murderous kleptomania. Whatshername from Dead Space, yelling at you to fix everything while she sits behind a monitor eating cakes. [...]
Females in this vein don't come across as "independent" or "strong." They act like neurotic feminists who feel that their every action and expression has to illustrate the fact that they're just as capable as the men, and don't like being looked upon amorously (hence why they all dress so conservatively, I suppose). They're as shallow as any traditional kidnapped princess because they only have one character trait, and still define themselves by the men that surround them.
You want to make a strong female character, you do the same thing you do to make a strong anything character. Give them a life, a backstory, hopes, dreams, desires. Give them the capacity to feel the whole gamut of emotions. Yes, let them be tough, but let them laugh, and cry, and find things to enjoy in life. And why not give them a wazza pair of jugs, too. That's always fun.