Not a fan of reviving dead threads but this might be useful for other people who stumble on this thread in the future.
Keep in mind that you're 15 and acne is normal - as undesirable as it is.
But there are some measures you can take to make things better. Your habits will play a big role in your acne breakouts.
- Take a shower after you work out or once a day
- Wear a clean shirt that's been washed with simple detergent after your shower
- Don't place yourself in situations where you will sweat too much i.e. wear appropriate layers of clothing when you're going about your business in winter or summer or what-have-you
- Wash your bedsheets regularly, at least once every week or every two weeks
- Stop drinking carbonated beverages like Cola... leave the coke to when you get to the clubs when you get older and mix it with rum instead

- Drink clean, filtered water, just an extra glass or two a day
- Use simple soaps, as suggested Ivory or Dove are great soaps
- I've heard that salycylic acid ointments or solutions dabbed onto the face and skin help, so that may help too
Lastly, the most important thing about these pointers is that they are all habits - you have to be consistent with them.