1. 80% of what your body will look like is diet-dependent. Therefore it is not enough to exercise and eat crap. First you need to establish a limit on how many calories you'll eat a day, and then split it up into 6 mini-meals a day spaced ~3 hrs apart. The constant supply of food keeps your metabolism running at a higher level, so you burn more of it as energy and store less of it as fat. The amount of calories consumed per day is critical.

2. 20% of what your body will look like is still exercise-dependent. 3 days of cardio to burn calories, and 3 days of weight lifting to increase muscle mass. More muscle means a higher metabolism so you burn off calories quicker. Also, 1 pound of muscle is much denser than 1 pound of fat, so not only does it take up less space, but it looks healthier as well.

3. Drink a gallon of water a day. A lot of the time when we think we're hungry, we're really just thirsty. So drink up.

4. Get a good amount of sleep. Sleep deprivation slows down your metabolism.

Nothing earth-shatteringly new, but these are tried and true principles that professional nutritionists teach. Consistency in following them is the key, as it is to most endeavors in life.