I started in Judo, learning basing falling and throwing, and moved into Aikido, Jujitsu and Karate when I was a bit older, and mature enough to begin the offensive training more seriously. I believe that was about 13 years old (I started defensive forms, Judo, at 7), and I stopped at about 16, on my last, second to last, and third to last belts (for each form).
Since then, I also took a three week course on \'streetfighting\', which I took from a career cooler, when I began looking into becoming a police officer. I think that martial arts will be more practical though - street fighting, at least the style I learned, is all about putting your man down quickly and painfully, and will probably cause some lasting damage (especially to the knees).