Watch your diet. Stay away from junk food. When I was a teen, I got a lot of exercise out in the fresh air and sunshine - rode my bike two miles a day, planted and tended a little garden, stuff like that - and ate more fresh foods (like salads and veggies) than fatty stuff and very little meat. I didn't have a bad problem with pimples. Next, you need to wash your face twice a day (morning and evening is good) with a good oil and dirt remover that won't dry your skin out. I used to us "PropaPh" but I'm not sure if they make it any more. (Yeah, it was that long ago)
For breakouts, I used over the counter stuff, although Clearasil didn't do much for me. Be careful about squeezing, because you can make matters worse!
The products the others have recommended may be very good, too, but I would say that in addition to them, eat well and keep your skin clean.