Check out this great TED video that discusses raising brave girls who will take on the world with bravery instead of striving for perfection.
I think this is a great talk that can easily be related to soccer. We should push girls to be brave on the soccer field. I believe that means different things for each player. Bravery for some might be just trying soccer for the first time. Others might need bravery to tryout for a select team if they are not sure they will make the team. Being brave does not mean being good. Bravery is putting yourself in situations where you might fail.
Let me know what you think of the video.