A healthy diet should consist of just the right amount of calories daily based on your height, body weight, and age. This number is usually between 2000-3000.
For this daily caloric intake you should have no more than 10% of that coming from fat. Most of the caloric intake should be from protein or carbohydrates.
Above basic calorie counting you should eat lots of fruits and vegetables daily because they are nutritious, high in vitamins and dietary fiber. Also, it is a good idea to eat whole grains and as little processed foods as possible. It's always a good idea to eat foods that are all natural and organic.
Also you should drink lots of water daily to stay hydrated.