Pick up a camera. Shoot something. No matter how small, no matter how cheesy, no matter whether your friends and your sister star in it. Put your name on it as director. Now you're a director. Everything after that you're just negotiating your budget and your fee.
It's quite funny in that I once won Rear of the Year at my school! I was about 17 in the sixth form and we used to have an end of year celebration and give out different awards. I even got a little trophy!

