I Am 5ft 6in 15 Year Old Female. What Is A Good Diet To Stick To?

A healthy one.  Eat plenty of fruits and vegetables.  Opt for whole grain breads and pastas instead of white.  Drink water or 100% fruit juice instead of soda.  Avoid things with a lot of saturated fat or cholesterol.  Cut down on the meat, especially cow and pig meat.  

You should also be eating about six small meals throughout the day rather than the traditional three large meals.   Small, frequent meals help keep your metabolism running fast.  Starving yourself or eating infrequently, on the other hand, make your metabolism slow down so you burn fat even slower.