Can anyone give me an advice how to approach women?

I am a sensible, shy person, I had so many failures with girls/women. I like women so much, I really love them, I want to talk to them, to approach them. I see beautiful girls on the street, in the bus etc., I want to talk to them, to get in touch with them, but I hesitate... I am too tensed, too nervous. How do I get to that state of relaxation so that I can talk easily to a woman?