How do you become a professional makeup artist?

I am interested in becoming a make-up artist when i am older. I am currently about to go into 10th Grade and I have just realized that this is what I want to do! I have been asking around my family, but no one seems to know what I should to prepare myself!! I am curious about how you became one!! What classes should I take??? What should I do for college?? Are there any summer classes I need to do?? I was preparing myself for fashion designing before, but now I've changed and I"M CLUELESS!!!! My school offers a cosmetology classes for juniors and seniors, but that's all i know about!! Please please PRETTY PLEEEAAASSSEEE help me!!! i would love it ;)