There is perhaps nothing more attractive to a woman than confidence in a guy. Of course there is always a yin to the yang, and the opposite of that must also be true. If you are not confident in your own skin, then women are going to sense this in you.
If you are serious about getting more beautiful women into your life, then high self-confidence is a must. Forget about just being confident with women; this has to be an aspect of your personality that affects every area of your life.