Stay away from simple sugars, sugary drinks, soy(soy is highly processed, but most people don't know that) and processed foods. Eat whole foods, which consists of one ingredient. Sweet potato only ingredient is sweet potato. Brown rice is brown rice and so forth.
And of course, stay away from anything fried.
Good question! Highly recommend green tea. It's an antioxidant and will help you on losing weight as well...just a bit.
Have about 2 to 3 cups a day..and lots of water.
If you need to sweeten it, use stevia. Stay away from substitute sugar. It will only make you crave more sugar and all those chemicals are not good in your body.
I use one stevia and I add 3 whole cloves. Yummy!
Let us know a little bit more about yourself... your typical day of eating, including times. Physical activity... supplements. At this age it is VERY important to be taking a daily vitamin, especially one with folic acid. It's possible in the next 10 years you'll be having children and you need those lady parts nice and pumped up with the stuff, plus you're still growing and need plenty of Vitamin C & D, Calcium... amongst other things.